What is the correct answer?
4
A. [m₁ m₂/2(m₁ + m₂)] (u₁ - u₂)²
B. [2(m₁ + m₂)/m₁ m₂] (u₁ - u₂)²
C. [m₁ m₂/2(m₁ + m₂)] (u₁² - u₂²)
D. [2(m₁ + m₂)/m₁ m₂] (u₁² - u₂²)