In the following question, a sentence / a part of sentence is underlined. Below are given alternatives to the underlined part which may improve the sentence. Choose the correct alternative. In case no improvement is required, choose "No Improvement" option.
One night they sank through the shiny water, and for the first time since he has known them, began to quickly swim.

Options

A. he had known them, began to swim quickly
B. he have known them, begin to quickly swim
C. he knew them, began to swim quickly
D. No improvement

Answer

A