--- Hi, Ella, which is the ___________ street in your city?

--- High Street. Many people go shopping there.

A. busier B. quieter C. busiest D. quietest

C

句意：---你好，艾拉，你所在的城市里哪条街最繁忙？---高街。许多人去那购物。A表示更繁忙，B表示更安静，C表示最繁忙，D表示最安静。根据句意，这里用最高级，故选C。