The correct answer is: A. much
The word “much” is used to refer to an indefinite amount of something. In this case, the speaker is saying that there is not a lot of people in the place they are currently in.
The word “many” is used to refer to a large number of something. In this case, the speaker is not saying that there is a large number of people in the place they are currently in.
The word “a lot” can be used to refer to a large number of something or to a large amount of something. In this case, the speaker is not saying that there is a large number of people in the place they are currently in, so they are not using “a lot” in the sense of “a large number.” They are also not saying that there is a large amount of people in the place they are currently in, so they are not using “a lot” in the sense of “a large amount.”
The word “some” is used to refer to an indefinite number or amount of something. In this case, the speaker is saying that there is not a lot of people in the place they are currently in, so they are not using “some” in the sense of “an indefinite number.” They are also not saying that there is a large amount of people in the place they are currently in, so they are not using “some” in the sense of “an indefinite amount.”