What distinguishes active isolated stretching from other stretching exercises?
a. the motion of bouncing
b. the need for a partner
c. the likelihood of injury
d. the use of external objects

The question says, 'what distinguish active isolated stretching from other stretching exercises? The correct option is D. Active isolated stretching normally requires the use of external objects such as rope. Other forms of stretching do not require any form of external object for their performance. Active isolated stretching often lasts for about few seconds.

The answer is  the potential energy of the bob at position b is 1.47 joules.if the maximum height of the bob is 0.45 meters when it swings back,1.323   joules of energy was transformed to thermal energy.hope this