What does the number in the various Quadrature Amplitude Modulation levels, such as 16 in QAM-16 and 64 in QAM-64, indicate? (Choose the single best answer.)

What does the number in the various Quadrature Amplitude Modulation levels, such as 16 in QAM-16 and 64 in QAM-64, indicate? (Choose the single best answer.)
A . The number of spatial streams, which is the 1/4 the number in the QAM level
B . The speed of data transfer, which is four times the number in the QAM level
C . The number of target points in the QAM constellation, which are equivalent to amplitude and phase combinations
D . The channel width, which is stipulated in MHz

Answer: A