Among the given options, two are possible in the context of the sentence:
1. should have been
2. might have been
The best option depends on the intended meaning of the sentence. Let's examine each option to understand their implications:
1. should have been: This option implies that the person is expressing regret or missed opportunity. It suggests that the person didn't express gratitude at the time of the accident, but in hindsight, they now realize they should have been thankful for not getting hurt.
2. should be: This option is grammatically incorrect in the context of the sentence. It doesn't fit with the structure and meaning of the sentence.
3. might have been: This option implies uncertainty or possibility. It suggests that the person is considering the possibility that he might have been thankful in the situation, but it's not confirmed.
4. might be: This option is grammatically incorrect in the context of the sentence. It doesn't fit with the structure and meaning of the sentence.
The best option for the sentence would be:
He should have been thankful that he wasn't hurt in the accident instead of complaining about the damage to his car.
This option conveys a clear meaning of regret for not expressing gratitude at the time of the accident.