Answer: A
In the trans isomer the two bromines are on opposite faces of the ring, so a mirror plane through C2 and C5 (which would exchange C1 and C3) does not exist; it exists only in the cis isomer. The two stereocentres have the same descriptor, (1R,3R) or (1S,3S), and the molecule is chiral. Reflection changes both descriptors and gives the non-superimposable enantiomer; it cannot change a trans relationship into cis.