Answer: The correct option is (C) 0.5.
Step-by-step explanation: We are given to find the common ratio for the following geometric sequence :
2, 1, 0.5, 0.25, . . .
We know that
in a geometric sequence, the ratio of any term to its preceding term is the required common ratio of the sequence.
In the given sequence <a(n)>, we have

So, we get

Thus, the required common ratio for the given geometric sequence is 0.5.
Option (C) is CORRECT.