To divide 12.936 by 3.2 using the correct number of significant digits, we need to follow the rule that the result of a calculation should have the same number of significant digits as the measurement with the least number of significant digits.
In this case, 3.2 has two significant digits, while 12.936 has five significant digits. Therefore, the final result should have two significant digits.
Performing the division, we get:
12.936 ÷ 3.2 = 4.05
Rounding the result to two significant digits, we get:
4.05 ≈ 4.0
Therefore, the answer is C. 4.0.