As a Navy clinical psychologist assigned to a Marine operational unit , I was authorized to wear their uniform . The corporal rolled forward in his wheelchair and shook my hand firmly . " You have no idea how great it is to see that uniform , ma'am , " he said with a grin .

Choices:
[1]. Because he could n't be bothered to get up .
[2]. Because he was in a position of authority .
[3]. Because he had gotten there a while ago .
[4]. Because he had lost the use of his legs .
Answer the following question: Why was the corporal seated ?
[4].