The manager announced that the team's performance, as measured by project completion rates, was not only excellent but also deserving of a bonus.

✓ Correct Answer: Option B

The construction 'not only X but also Y' requires X and Y to be grammatically parallel. 'Excellent' is an adjective, and 'deserved a bonus' is a predicate verb phrase that correctly parallels 'was excellent' (implied verb 'was').