Michael is good . He's hardworking and __ to be the new manager. not too efficient not efficient enough efficient enough too efficient

The sentence is trying to express that Michael is good enough to be the new manager. The phrase "not efficient enough" fits this context because it suggests that Michael is not as efficient as needed, which contradicts the statement that he is good enough to be the new manager. The other options do not fit the context. "Not too efficient" and "too efficient" suggest that Michael is not efficient, which contradicts the statement that he is good enough to be the new manager. "Efficient enough" suggests that Michael is efficient, but it does not express the idea that he is not as efficient as needed. Therefore, the correct answer is "not efficient enough".