To calculate (7+3i)+(−8+9i),add the real parts of each complex number, 7+(−8)=−1,and then add the imaginary parts, 3i+9i=12i. The result is −1+12i. Choices B, C, and D are incorrect and likely result from common errors that arise when adding complex numbers. For example, choice B is the result of adding 3i and −9i, and choice C is the result of adding 7 and 8.