The correct option is
D was he
The question tag is a grammatical structure used to convert a declarative sentence into an interrogative. They are formed using the auxiliary or modal verb from the statement and the appropriate subject.
When the statement is negative, the question tag formed is positive. The same way, for positive statements we use negative question tags.
Option D: In the given statement, the auxiliary verb used is 'wasn't' (was not), the subject is 'Wallace'. The sentence is negative, hence the correct tag will be positive.
So, the question tag formed is: was + he
We use the pronoun 'he' to refer to Wallace, and not the name itself, to avoid repetition.
Hence option D is correct.
Options A and C: 'Wasn't he' and 'didn't he' are negative question tags and do not agree to the sentence. Hence they are incorrect.
Option B: 'Did he' consists of the auxiliary verb 'did'.
The question tag is formed for the independent clause (Wallace wasn't...), as opposed to the dependent clause (when he drove...).
The verb 'did' is implied in the dependent clause (did drive), hence we cannot form a question tag with 'did', and B is incorrect.