If two independent corrections each raise femur height, the total increase is:

• A. 2 mm
• B. 6 mm
• C. -2 mm
• D. 0 mm

Answer: (B)

The main idea is that independent effects add together. When two corrections operate independently, their effects on femur height simply sum. So the total increase is the sum of the two increases. If each correction raises height by 3 mm, two corrections give 3 mm + 3 mm = 6 mm. That’s why the total increase is 6 mm. The other numbers would require different per-correction amounts or compensating changes that aren’t present here.