‘Studying had paid off’ means

Directions: The passage is followed by five questions. Read the passage carefully and answer the question that follows. For the question four probable answers bearing options (1), (2), (3) and (4) are given. Only one out of those is correct. You have to choose correct answer.

The day of the maths test was next Monday. Jim had three days to study. He did not like maths. It was his hardest subject. He had to study in order to pass. He locked himself in his room. He turned off his phone and computer to avoid distractions. But, he could not solve a maths problem. He needed help. He had to turn on the phone and ask his friend for help. His friend agreed and came over. His friend helped him study for three hours. He took the test. He passed the test. Studying had paid off.