D. a generalization about the evidence you are going to present. This is the correct option.
Through the thesis, the writer expresses his/ her claim. This is what he / she wants to prove through the writing.For example, the overuse of smartphones cause communication problems between family members. This example reflects the writer's objective: to write about the problems of communication in families. Then, it also includes which factor affects the communication problem: the overuse of smartphones. Where has he/ she taken this generalization from? From evidence. This can be from reading or observing families. The generalization is this: all the family members that overuse smartphones have communication problems.
These options are not right:
A. a sentence that sums up the main idea of your composition. This sounds like the opening sentence of the concluding paragraph.
B. the audience and purpose of a composition. The thesis is addressed to an audience but this is not mentioned in the statement. The purpose is part of the thesis when the writer states: " In this paper, I will explain why the overuse of smartphones bewteen family members cause communication..." The underlined phrase shows the purpose.
C. an implied idea that will be developed throughout a paragraph . In complex papers, the thesis may be implied but througout the text not the paragraph. You need to read the whole paper to infer what the thesis is.