PHPのメールフォームの作成について　SESSION

PHPでメールフォームを作成しているのですが、セレクトボタンやラジオボタンの時にSSESIONを使用して情報を保存したいのですが、どうしても上手くいきません。
セレクトボタン＝応募職種
ラジオボタン＝性別
どのようなコードを書くべきでしょうか？
＊他は全てSESSIONで情報が保存されます。

```ruby:index.php
<?php
    session_start();

    $work = "";
    $furigana = "";
    $name = "";
    $sex = "";
    $age = "";
    $tel = "";
    $mail = "";
    $content = "";
    $skill = "";
    $performance = "";
    $motive = "";
    $errorWork = "";
    $errorName = "";
    $errorFurigana = "";
    $errorSex = "";
    $errorAge = "";
    $errorTel = "";
    $errorMail = "";
    $errorContent = "";
    $errorSkill = "";
    $errorPerformance = "";
    $errorMotive = "";

    if(isset($_SESSION['work']) && isset($_SESSION['name']) && isset($_SESSION['furigana']) && isset($_SESSION['sex'])
    && isset($_SESSION['age']) && isset($_SESSION['tel']) && isset($_SESSION['mail']) 
    && isset($_SESSION['content']) && isset($_SESSION['skill']) && isset($_SESSION['performance']) 
    && isset($_SESSION['motive'])){
        $work = !is_null($_SESSION['work']) ? $_SESSION['work'] : "";
        $name = !is_null($_SESSION['name']) ? $_SESSION['name'] : "";
        $furigana = !is_null($_SESSION['furigana']) ? $_SESSION['furigana'] : "";
        $sex = !is_null($_SESSION['sex']) ? $_SESSION['sex'] : "";
        $age = !is_null($_SESSION['age']) ? $_SESSION['age'] : "";
        $tel = !is_null($_SESSION['tel']) ? $_SESSION['tel'] : "";
        $mail = !is_null($_SESSION['mail']) ? $_SESSION['mail'] : "";
        $content = !is_null($_SESSION['content']) ? $_SESSION['content'] : "";
        $skill = !is_null($_SESSION['skill']) ? $_SESSION['skill'] : "";
        $performance = !is_null($_SESSION['performance']) ? $_SESSION['performance'] : "";
        $motive = !is_null($_SESSION['motive']) ? $_SESSION['motive'] : "";
    }

    if(isset($_SESSION['error_work']) && isset($_SESSION['error_name']) && isset($_SESSION['error_furigana']) && isset($_SESSION['error_sex'])
    && isset($_SESSION['error_age']) && isset($_SESSION['error_tel']) && isset($_SESSION['error_mail']) 
    && isset($_SESSION['error_content']) && isset($_SESSION['error_skill']) && isset($_SESSION['error_performance'])
    && isset($_SESSION['error_motive'])){
        $errorWork = $_SESSION['error_work'] ? 1 : 0;
        $errorName = $_SESSION['error_name'] ? 1 : 0;
        $errorFurigana = $_SESSION['error_furigana'] ? 1 : 0;
        $errorSex = $_SESSION['error_sex'] ? 1 : 0;
        $errorAge = $_SESSION['error_age'] ? 1 : 0;
        $errorTel = $_SESSION['error_tel'] ? 1 : 0;
        $errorMail = $_SESSION['error_mail'] ? 1 : 0;
        $errorContent = $_SESSION['error_content'] ? 1 : 0;
        $errorSkill = $_SESSION['error_skill'] ? 1 : 0;
        $errorPerformance = $_SESSION['error_performance'] ? 1 : 0;
        $errorMotive = $_SESSION['error_motive'] ? 1 : 0;
    }
?>
    <!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>phpでフォーム送信</title>
</head>
<body>
<form action="./confirm2.php" method="post">
    <div id="contents">
        <div>
            <label>応募職種</label>
            <select name="work">
                <option value="<?php echo $errorWork; ?>">選択してください</option>
                <option value="<?php echo $work; ?>">エンジニア</option>
                <option value="<?php echo $work; ?>">デザイナー</option>
                <?php if($errorWork) echo "入力に誤りがあります"; ?>
            </select>
        </div>
        <div id="name">
          お名前　<input type="text" name="name" value="<?php echo $name; ?>">
          <?php if($errorName) echo "入力に誤りがあります"; ?>
        </div>
        <div id="furigana">
          フリガナ　<input type="text" name="furigana" value="<?php echo $furigana; ?>">
          <?php if($errorFurigana) echo "入力に誤りがあります"; ?>
        </div>
        <div id="age">
          年齢　<input type="text" name="age" value="<?php echo $age; ?>">
          <?php if($errorAge) echo "入力に誤りがあります"; ?>
        </div>
        <div>
            <label>性別</labal>
            <input type="radio" name="sex" value="<?php echo $sex; ?>">男性
            <input type="radio" name="sex" value="<?php echo $sex; ?>">女性
        </div>
        <div id="tel">
          電話番号　<input type="text" name="tel" value="<?php echo $tel; ?>">
          <?php if($errorTel) echo "入力に誤りがあります"; ?>
        </div>
        <div id="mail">
          メールアドレス　<input type="text" name="mail" value="<?php echo $mail; ?>">
          <?php if($errorMail) echo "入力に誤りがあります"; ?>
        </div>
        <div id="content">
          職務経歴　<textarea name="content"><?php echo $content; ?></textarea>
          <?php if($errorContent) echo "入力に誤りがあります"; ?>
        </div>
        <div id="skill">
          スキルシート　<textarea name="skill"><?php echo $skill; ?></textarea>
          <?php if($errorSkill) echo "入力に誤りがあります"; ?>
        </div>
        <div id="performance">
          実績　<textarea name="performance"><?php echo $performance; ?></textarea>
          <?php if($errorPerformance) echo "入力に誤りがあります"; ?>
        </div>
        <div id="motive">
          志望動機　<textarea name="motive"><?php echo $motive; ?></textarea>
          <?php if($errorMotive) echo "入力に誤りがあります"; ?>
        </div>
        </br>
        </br>
        <input type="submit" value="確認">
    </div>
</form>
</body>
</html>
```

```ruby:confirm2.php
<?php
    session_start();

    $work = validateData("work");
    $name = validateData("name");
    $furigana = validateData("furigana");
    $sex = validateData("sex");
    $age = validateData("age");
    $tel = validateData("tel");
    $mail = validateData("mail");
    $content = validateData("content");
    $skill = validateData("skill");
    $performance = validateData("performance");
    $motive = validateData("motive");

    if(!filter_var($mail, FILTER_VALIDATE_EMAIL)){
        $_SESSION['error_mail'] = 1;
    }

    if($_SESSION['error_work'] || $_SESSION['error_name'] || $_SESSION['error_furigana']
    || $_SESSION['error_sex'] || $_SESSION['error_age'] || $_SESSION['error_tel'] 
    || $_SESSION['error_mail'] || $_SESSION['error_content'] || $_SESSION['error_skill'] 
    || $_SESSION['error_performance'] || $_SESSION['error_motive'] ){
        header("Location: ./index.php");
        exit();
    }

    function validateData($key){
        if(is_null($_POST["$key"]) || empty($_POST["$key"]) || !is_string($_POST["$key"])){
            $_SESSION["$key"] = $_POST["$key"];
            $_SESSION["error_" . $key] = 1;
            return "";
        }else{
            $_SESSION["$key"] = $_POST["$key"];
            $_SESSION["error_" . $key] = 0;
            return $_POST["$key"];
        }
    }
    ?>
    <!DOCTYPE html>
<html>
<head>
<meta charset='UTF-8'>
<title>確認画面</title>
</head>
    <body>
        希望職種：<?php echo $work; ?>
        </br>
        お名前：<?php echo $name; ?>
        </br>
        フリガナ：<?php echo $furigana; ?>
        </br>
        性別：<?php echo $sex; ?>
        </br>
        年齢：<?php echo $age; ?>
        </br>
        電話番号：<?php echo $tel; ?>
        </br>
        メールアドレス：<?php echo $mail; ?>
        </br>
        職務経歴
        </br>
        <?php echo $content; ?>
        スキルシート
        </br>
        <?php echo $skill; ?>
        実績
        </br>
        <?php echo $performance; ?>
        志望動機
        </br>
        <?php echo $motive; ?>
        </br>
        </br>
        <form action='./complete2.php' method='post'>
            <input type='button' onclick='history.back()' value='戻る'>
            <input type='submit' value='確認'>
        </form>
    </body>
</html>
```