The Moon's South Pole-Aitken Basin Is the Largest Known Impact

The Moon's South Pole-Aitken Basin is the largest known impact crater in the solar system. Yet it was never mentioned by the seventeenth-century astronomers who named most of the Moon's prominent features. What do we believe is the reason for this?

A) Seventeenth-century telescopes were not adequate to resolve the Basin.
B) The Basin is of very recent origin, after the seventeenth century.
C) Dust storms on the Moon have only recently uncovered the Basin.
D) The Basin is on the far side of the Moon.