Explanation:

The correct answer to the given question is option 'C' - 6 billion. Here's the explanation:

World Population in 1997:
In 1997, the world population was estimated to be around 6 billion. This figure represents the total number of people living on Earth at that time.

Population Growth:
Over the years, the world population has been steadily increasing due to factors such as advances in medical technology, improved living conditions, and a decrease in infant mortality rates. This has led to a significant growth in the global population.

Factors Influencing Population Growth:
Several factors contribute to the growth of the world population:
1. Birth Rate: The number of births per 1,000 individuals in a population. Higher birth rates lead to population growth.
2. Death Rate: The number of deaths per 1,000 individuals in a population. Lower death rates result in population growth.
3. Fertility Rate: The average number of children born to a woman during her reproductive years. Higher fertility rates lead to population growth.
4. Life Expectancy: The average number of years a person is expected to live. Increased life expectancy contributes to population growth.

Current World Population:
As of now, the world population stands at approximately 7.9 billion as per the latest estimations. This number is significantly higher than the population in 1997. The increase in population can be attributed to advancements in healthcare, improved sanitation, and increased access to education.

Population Projections:
Population projections suggest that the world population will continue to grow in the coming years. However, the rate of growth is expected to slow down due to declining fertility rates in many countries and efforts to control population growth.

In conclusion, the present population of the world in 1997 was estimated to be around 6 billion. The world population has been steadily increasing over time, and the current estimate is approximately 7.9 billion.

6 billion ,,,,,as referred to ncert