Select the most appropriate option, out of the five options given for each of the following sentences, which in your view, should be grammatically and structurally correct. Please note that the meaning and the context of the sentence must not change.

Options

A. They have been playing in the garden since it has begim to rain.
B. They have been playing in the garden since it had begun to rain.
C. They had played in the garden since it had begun to rain.
D. They were playing in the garden since it began to rain.