In the answers it seems like we are assuming the numbers are positive integers. Which is not what the choices say. It could be positive or negative and in that case you cannot conclude the number of integers between the numbers a and b as 6.

-1 is greater than -8. Their difference is 7 but the number of integers will be 8.

Don´t count the -1 and -8. The statement only says greater than or less then, not equal to.

The number of integers between -1 and -8 will still be six.

Actually, if we have two integers, no matter where they are on the number line, if a-b=7, they'll have the same number of integers (6) between them.
If we have 8 and 1, we have 2, 3, 4, 5, 6, and 7 in between.
If we have -8 and -1, we still have 6 numbers in between.

However, if we have 1.5 and 8.5, we have 7 numbers in between (2, 3, 4, 5, 6, 7, and 8) instead of 6. This is the key to this problem.

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