Since the angles are acute andsin(a°)=cos(b°), it follows from the complementary angle property of sines and cosines that a+b=90. Substituting 4k−22 for a and 6k−13 for b gives (4k−22)+(6k−13)=90, which simplifies to 10k−35=90. Therefore, 10k=125, and k=12.5. Choice A is incorrect and may be the result of mistakenly assuming that a+b and making a sign error. Choices B and D are incorrect because they result in values for a and b such that sin(a°)≠cos(b°).