A possibly trick EFL question

I teach EFL for an after school program in a non-English speaking country. My students just had final exams at school, EFL being one of them. One student ask which of the following passages is GRAMMATICALLY incorrect, discounting word choice or style:

"I can't believe the zoo keeper made you feed the snake. That was so cool."

Or

"My boss makes me get him coffee, pick up his cleaning and buy presents for his wife. He can't do anything by himself."

I'm stumped.