system
Given the following post, respond as if you're commenting on Reddit:
human
[The Martian] Were potatoes the only kind of food crop that Mark Watney could grow and survive on in his situation or could something else have been substituted in their place if he had them?
gpt
He could have done. The key though was maximum calories per unit area. He had vitamins in tablet form. Potatoes worked well there.

In the book he mentioned there were a few other vegetables, but went for potatoes for space efficiency.