How do you find the frequency of a recorder?

Modern recorders are most commonly pitched at A=440 Hz, but among serious amateurs and professionals, other pitch standards are often found. For the performance of baroque music, A=415 Hz is the de facto standard, while pre-Baroque music is often performed at A=440 Hz or A=466 Hz.

Explanation:

is there multiple choice answers?

im not exactly sure but i think its b!