Find the odd number / letters / word from the given alternative:

The answer is D. 9748.

In each of the other options, the sum of the first two digits is equal to the third digit. For example, in 5788, the sum of 5 and 7 is 12, which is equal to 8. However, in 9748, the sum of 9 and 7 is 16, which is not equal to 4.