Your pituitary lactotrop cells hypertrophy during pregnancy to produce increasing amounts of prolactin - part of the pathophysiology of Sheehan's syndrome... increased blood loss during delivery can cause ischemic necrosis of pituitary

I don't think this question was going after pregnancy related increase in prolactin. That could lead you to the correct answer, but imo, they mentioned she had an MRI for head trauma, which could mean there was damage to the pituitary stalk, in which case the ONLY hormone which will increase when there is damage to the stalk is prolactin, because it is under constant inhibition by dopamine. Prolactin obviously stimulates lactotropes.

This was just how I got to the answer. You could very well have gotten to the correct answer by simply using the pregnancy logic, its probably easier.