I want to find if the above molecule shows cis-trans isomerism, per an assignment. I am assuming that such isomerism, if present, will be shown by the substituted chlorines.
It seems clear to me that the two chlorines in the picture lie in different planes. Therefore, the molecule will show optical isomerism, not cis-trans. However, the answer key says that it shows both optical and cis-trans isomerism.
I think the answer key is wrong. But if it is right, could someone please explain to me how this molecule shows cis-trans isomerism?