Regarding brain development in early childhood, which of the following statements is true?
a. increases in brain size are primarily due to myelination and increases in the number and size of nerve endings.
b. the most rapid period of brain growth throughout the lifespan occurs during early childhood.
c. the prefrontal cortex experiences a growth delay during the process of myelination.
d. there are very few anatomical changes in the brain from ages 3 to 6.

Answer is A. Increases in brain size are primarily due to myelination and increases in the number and size of nerve endings.

Explanation:

Myelination is the process which leads to the formation of myelin sheath around axon or nerve impulse.

The myelin formed is a coating rich in fat, that is found around the axon of neuron. It protects the neuron, and at the same time helps the neuron to conduct signals or impulses move quickly and efficiently.

advantage of using stem cells in medical research:

1.       it provides medical benefits in the fields of therapeutic cloning and regenerative medicine.

2. it provides great potential for discovering treatments and cures to a variety of diseases including parkinson disease, spinal cord injuries, diabetes, alzheimer’s disease and many more.

3. limbs and organ could be grown in lab from stem cells and then used in transplant or treat illness.

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.