TASK DEFINITION: In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
PROBLEM: Sentence1: Alfred hated how hot the beach sand was. Sentence2: He found wearing sandals in the sand equally unpleasant. Sentence3: He was determined to invent a solution. Sentence4: Alfred devised a heat-resistant lotion for his feet. Sentence5: He tried to gather capital to bring it to market but failed.

SOLUTION: Alfred

PROBLEM: Sentence1: Jena was cooking spaghetti for dinner. Sentence2: She went pick up the groceries from the store. Sentence3: The tomatoes appeared to be rotten. Sentence4: Jena picked up a jar of spaghetti sauce. Sentence5: She used pre made sauce instead of homemade.

SOLUTION: Jena

PROBLEM: Sentence1: Jeff thought he was better at ping pong than his sister Jennifer. Sentence2: Jennifer didn't agree so she challenged him to a game. Sentence3: It was a close game all the way until the end. Sentence4: Jennifer beat Jeff by two points. Sentence5: Jeff shook her hand and agreed she was the better player.

SOLUTION:
Jennifer, Jeff