Let's analyze each statement:
A. The sum of the measures of two supplementary angles is 180°.
- Always True. By definition, supplementary angles are two angles whose measures add up to 180°.
B. The sum of complementary angles is 180°.
- Never True. Complementary angles are defined as two angles that add up to 90°, not 180°.
C. Two adjacent angles are complementary.
- Sometimes True. While adjacent angles can be complementary (for example, if one angle measures 30° and the adjacent angle measures 60°), they can also be supplementary (e.g., one measuring 120° and the adjacent one measuring 60°) or have other relationships. Therefore, this statement is only sometimes true.
In summary: A. Always True B. Never True C. Sometimes True