Answer: C) 3.2
The answer cannot be choice A as -2.8 is not between 2 and 4
The answer is not B either. While 3 is between 2 and 4, it is an integer when Trina guessed something that wasn't an integer.
After crossing A and B off the list, the only thing left is choice C. The value 3.2 is between 2 and 4, also it is a non-integer as it has a decimal portion 0.2