Which sentence contains a pronoun that is not in the proper case?

a)
the principal decided that the ultimate decision about dress code should be left to we students.

b)
my parents feel that we cannot be left home alone until we prove we are not easily spooked by noises.

c)
if we don't try to figure out a way to curb smoking in this town, health statistics will continue to fall.

d)
we hunters know that killing deer does not mean we don't value animal wildlife; in fact, it means the opposite.