When two lines intersect, they create angles that are related to each other. Angles A and C are opposite angles (also called vertical angles), and angles B and D are also opposite.
Given that \( m∠C = 75° \):
- Because angles A and C are vertical angles, we have \( m∠A = m∠C = 75° \).
Therefore, \[ m∠A = 75° \]
The correct answer is \( 75° \) (75 degrees).