The correct answer is: B. The caretaker said that he would put the key there.
The sentence “I will put this key here,” said the caretaker. is in the simple present tense. This means that the action is happening now or will happen in the near future. In this case, the caretaker is saying that he is going to put the key down right now.
The other options are incorrect because they do not accurately reflect the tense of the original sentence. Option A, “The caretaker says that he would put the key there,” is in the past tense. This would be correct if the caretaker had already put the key down, but he has not done so yet. Option C, “The caretaker says that he would put the key here,” is also in the past tense. This would be correct if the caretaker was planning to put the key down in the past, but he is not planning to do so now. Option D, “The caretaker said that he will put the key there,” is in the future tense. This would be correct if the caretaker was planning to put the key down in the future, but he is planning to do so now.
In conclusion, the correct answer is B. The caretaker said that he would put the key there.