Translation:The man is an officer in the police force.
'The man is an officer in the police' was marked wrong. Is it really not an appropriate translation?
Nothing wrong, as far as I can see. There is no context issue. I added it, thank you. ^.^
Marked me wrong for putting "police" without the addition of "force" too. It is acceptable English to just use the word "police" and seems like a reasonable translation of the Greek text.
The goal of this course is to help people learn a new language. The fact that one can infer that a police officer has probably something to do with a police station doesn't mean that we should use "police station (=αστυνομικό τμήμα)" as a translation for "αστυνομία".
"the man is officer in the police force" was marked wrong, is the article mandatory here?