Choose the synonym of the given word: 

Copious

A synonym is a word which is analogous in meaning to another word.

Let us look at a many examples of synonym.

For illustration, let us take the word ‘ uncertain ’. The word uncertain means to be not sure about commodity. You're uncertain about which dress to wear to the party. A synonym for ‘ uncertain ’ is doubtful. You are doubtful about which dress to wear to the party. Both the rulings convey the same meaning.

Now let us see the meaning of copious. Since copious refers to commodity which is abundant in volume, the reverse is option d, that is, generous and plentiful.

therefore, the answer is option d.