Aflat character
is a well-developed character
changes, or grows, according to occurrences in his life
has only one or two developed traits

Flat characters do not change throughout the story, therefore it can not be "changes, or grows, according to occurrences in his life". Flat characters are also not that complicated so that means it can't be "is a well-developed character "... 
Which means the correct answer is
 "has only one or two developed traits"

B. alice is pretending there is a way through the glass when in reality that would not be physically possible therefore she has to pretend. but i think d is also possible because alice notices the glass is actually melting away which is also not possible either