Answer: B. voice gets deeper and growth of facial hair
Puberty can be defined as physiological, morphological and anatomical changes that occur in a human body. It is a stage of growth which forms transition between childhood and adulthood. It starts in the age of 8- 12 years. It is caused by the release of the androgen, and testosterone hormones which brings changes. The changes like deepening of voice and growth of the facial hair are the examples of signs that develop in boys during puberty.
when the ball rolls down a hill potential energy conversion takes place to kinetic energy. and when it starts rolling down the hill, then kinetic energy=1/2mv^2
