Answer:
b. educational work completed after finishing after completing a first degree.
Explanation:
referring to dictionary, the word postgraduate in the sentence is an adjective. it means, "relating to or denoting a course of study undertaken after completing a first degree
look at the options. a, "educational work ✓ completed before completing a degree x", which is eliminated. b, "educational work ✓ completed after finishing another degree ✓" -> although the phrase in the answer "finishing another degree" is incorrect according to the meaning in dictionary, this is our closest answer, so therefore we choose b.
