Option C: acute angles
Step-by-step explanation:
Option A: Obtuse angles
Obtuse angle is an angle which is more 90° and less than 180°. Complementary angles are angles whose sum is 90°. Hence, Obtuse angles is not a correct answer.
Option B: Supplementary angles
Supplementary angle is an angle whose sum is 180°. Complementary angles are angles whose sum is 90°. Hence, Supplementary angles is not a correct answer.
Option C: Acute angle
Acute angle is an angle which is less than 90°. Complementary angles are angles whose sum is 90°. Hence, Acute angle is the correct answer.
Option D: Linear pairs
Two angles are said to be linear if the sum of two angles is 180°. Complementary angles are angles whose sum is 90°. Hence, Obtuse angles is not a correct answer.
Hence, If two angles are complementary angles they can be acute angles.