The following sentence has been divided into parts. One of them contains an error. Select the part that contains the error from the given options. This question / is quite too / simple for me / to answer.

Identify which part of the sentence has an error: These kind of trousers/ (A) are rather/ (B) expensive to buy./ (C) No error (D)

Find the part of the sentence that has a grammatical error: 'The citizens of the area longed on rain, which is natural when it is so terribly dry year-round.'