If he were in better shape, he would be a great addition to the team.
Answer: D. Were
Reasoning:
If he are in better shape, he would be a great addition to the team.
Makes no sense.
If he be in better shape, he would be a great addition to the team.
makes no sense.
If he is in better shape, he would be a great addition to the team.
makes no sense.
If he were in better shape, he would be a great addition to the team.
Makes sense!