Speed reading is concerned with:

A. how fast you read.
B. the number of words read in a minute.
C. reading rate as well as comprehension of what was read.
D. recalling three main points in three minutes.

is it C

It should be c. But data haven't shown that there's correlation between speed reading and comprehension.

D. recalling three main points in three minutes.

Yes, the correct answer is C. Speed reading is concerned with both the reading rate (how fast you read) as well as the comprehension of what was read. Speed reading techniques aim to increase the reading speed without sacrificing understanding and retention of the material.