(A) Incorrect . For the errors mentioned above.
(B) Incorrect . For the following reasons:
- "not X yet Y" is non-idiomatic.
- The structure in the "not" part has a clause after "sign" whereas in this option, the structure in the "yet" part has a prepositional phrase after "sign". Even though this is not a deterministic error, it is better to have as much parallel structures as possible.
- "sign of households' confidence that it was safe for them" is an indirect and wordy way to express the same idea expressed directly and concisely in option D.
(C) Incorrect . For the following reasons:
- The element after ?not? i.e. "as a sign_" is not parallel to the element after ?but? i.e. "a sign_"
- Problem no. 2 of option B
(D) Correct . The structures after "not" and "but" are completely parallel. "not X but Y" is the correct idiom.
(E) Incorrect . For the following reasons:
- "not X but also Y" is non-idiomatic. This structure also distorts the meaning since "also" indicates that the second part is in addition to the first part. On the contrary, the second part is a alternative to the first part.
- The position of "safely" is incorrect. "safely" should appear after "to".