Option: D is the correct answer.
D) -10
We are given a expression as:
(-5 + 8i) + (-5 − 8i)
i.e. the expression is a addition of two complex numbers.
Hence, we combine the like terms in the given expression.
i.e. we write the expression as:
(-5 + 8i) + (-5 − 8i)= (-5-5)+(8i-8i)
(-5 + 8i) + (-5 − 8i)= -10+0.i
(-5 + 8i) + (-5 − 8i) = -10
Hence, the complex number is represented in standard form as:
-10