The correct answer is D.

Explanation: The sentence "It might not look such a rosy proposition" needs a phrase that indicates the perspective from which the proposition is being evaluated.

- D. From his point of view best completes the sentence because it correctly indicates that the proposition might not seem favorable when considered from someone else's perspective.

Other options:
- A. From his viewing proposal: This is awkward and unclear.
- B. When he view the proposal: This is grammatically incorrect; it should be "views" instead of "view."
- C. Having viewed the proposal: This does not fit well with the context of comparing perspectives.
- E. From his seeing it: This is less precise and less commonly used than "From his point of view."

Thus, "From his point of view" best completes the sentence.