Statement 1: - It gives the average of the four numbers hence the total is 100. This is not sufficient. But this information is not sufficient to deduce for the largest number among four.

Statement 2: - W, X, and Y are less than 24. But does not provide any information about Z. Hence this is not sufficient.

Hence both statement alone are not sufficient to conclude which number is the largest.

Combining both : - Four numbers average is 25 which gives the sum of four number as 100. AND W, X, and Y are less than 24 so Z must be greater than 24 and in turn is the largest one.

Hence the answer is C and not the B.