Question 4
When is the tension (T) in a thread equal to the weight (W) of the object hanging from it?
The right answer is the one marked above.
Only while the object is in equilibrium. T = W is a consequence of equilibrium, not the definition of tension.
Haul the object upward and the tension exceeds the weight; cut the thread and the tension becomes zero while the weight is unchanged. The two are equal only at rest.