D is the incorrect statement (hence correct option). Read about chirality and R-S nomenclature and that will definitely help you. Both of these molecules (A and C) come out to be the same in terms of R-S configuration. Hence they are identical molecules.
A shortcut is: when you rotate the molecule about chiral cetre once (90 deg), its configuration is reversed. Rotating it one more time will again lead to inversion and thus the the same configuration (that may ‘look’ different but are the same).