The correct option is C Amicable
Option D: The word 'amicable' means 'characterized by friendliness and absence of discord'. When placed in the sentence, it means that 'both the parties were interested in a friendly/polite settlement'.
Hence this word is most suitable and option D is correct.
Option A: 'Enviable' refers to something that causes envy. The word isn't appropriate for this sentence. Hence A is incorrect.
Option B: 'Inimical' means 'unfriendly' or hostile. The sentence mentions a settlement. It means that two parties are trying to solve a conflict. Solving a conflict would require peace and not hostility. Hence this word wouldn't be appropriate for the sentence and B is incorrect.
Option C: 'Worthy' means 'deserving (attention or respect)'. It isn't appropriate for this sentence, hence C is also incorrect.