Which among the following is never possible as an output for a float?

Answer: Option D

In C, a float can represent both whole numbers and decimal numbers due to its ability to store values in floating-point format.

Option A: 3.666666 is a valid float representation with precision.

Option B: 3.666 is also a valid float value, just with fewer decimal places.

Option C: 3 is an integer, but it can still be represented as a float (e.g., 3.0).

Therefore, all the options listed are valid float outputs depending on how the float is stored or printed.

Hence, the correct answer is Option D: None of the mentioned.