If the dividend and divisor have unlike signs, then the sign of the quotient is _________.

The correct answer is: Negative

When the dividend and the divisor are of unlike signs, the quotient would be negative. That is,
When the dividend is negative and the divisor is positive or vice versa, there would always be a negative sign which would be passed on to the answer. Thus, making the quotient negative.
Hence, the correct answer is option b.