B (8 < log2(500) < 9).
28 = 256 and 29 = 512.
If you successively divide by two, starting with 500 and rounding down to the nearest integer where necessary, you get
500 |
250 |
125 |
62 |
31 |
15 |
7 |
3 |
1 |
If you successively divide by two, starting with 500 and rounding up to the nearest integer where necessary, you get
500 |
250 |
125 |
63 |
32 |
16 |
8 |
4 |
2 |
1 |
Putting those together, you see that log2(500) must lie between 8 and 9.