Answer:
The correct answer is b. better hygiene and food.
Explanation:
Human growth rate has accelerated in recent centuries because of the availability of better nutrition, hygiene, and health care. Unhygienic condition and lack of health care was the reason for the high mortality rate in early times which helps in making a disease epidemic that kills thousands of people in a short period.
But due to advances in technology in food, and health field people started to follow better hygiene and getting good nutrition and health care which helped in increasing the life expectancy in people during recent centuries. So the right answer is b.
