Option A: 'Ex' means 'out of' or 'former'. Here, 'ex-wife' refers to someone's previous wife, who is no longer their wife anymore. 'Former' expresses the previous, or past. So, it denotes time and option A is correct.
Option B: 'Size prefixes' include 'micro, macro'.
Option C: 'Number prefixes' include 'mono, uni, bi, tri, etc.'
Option D: 'Place prefixes' include 'circum, inter, intra, etc.'
These types of prefixes do not express time. Hence options B, C and D are wrong.