Answer:
Option D is the correct answer.
Step-by-step explanation:
By Pythagoras theorem we have
Hypotenuse² = Base² + Perpendicular²
Here hypotenuse = 7 mm
Let us consider other leg length given as base length
Base = 3 mm
So we have
7² = 3² + Perpendicular²
Perpendicular² = 40
Perpendicular = 6.3 mm
Other leg is 6.3 mm long.
Option D is the correct answer.