Find the missing number?

8
5
7
6

The answer is 6.

The missing number is the number that completes the sequence. The sequence is a series of numbers that are each one less than the number before it. So, the first number is 8, the second number is 7, the third number is 6, and so on.

Option A is incorrect because 8 is not one less than 7.

Option B is incorrect because 5 is not one less than 6.

Option C is incorrect because 7 is the third number in the sequence, not the missing number.

Option D is correct because 6 is the missing number in the sequence.