The correct option is D decline
The word that means the same as the italicized word in both the sentences is option D 'decline'. Decline means politely refuse. It also means gradual reduction in strength, numbers or quality. Sentence I means that he couldn't decline to accept his proposal. Sentence II means that country is witnessing a decrease in moral standards of political leaders. Option A 'retrograde' means moving backwards. Option B 'refute' means prove to be wrong. Option C 'droop' means bend or sag. Thus, the best fit for both the sentences is option D, decline and other options A, B and C are incorrect.