At times,the ligaments are overstretched or torn. This condition is called:

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$:
Osteoporosis is characterised by decreased bone mass and increased chances of fractures.
Reason $(R)$:
Common cause of osteoporosis is increased levels of estrogen.
In the light of the above statements,choose the most appropriate answer from the options given below:

Decreased level of oestrogen in the human body leads to:

Choose the correct pair.

Which of the following disorders affects the neuromuscular junction $(\text{NMJ})$ leading to fatigue,weakening,and paralysis of skeletal muscle?

Assertion: Inflammation of a skeletal joint may immobilize the movements of the joint.
Reason: Uric acid crystals in the joint cavity and ossification of articular cartilage lead to this.