At present, the world population is increasing at the rate of around
A. 2 %
B. 2.25 %
C. 2.5 %
D. 3 %
E. 1.8 %

Hint: Population growth is defined as the number of increase in individuals in a population in a given time. The formula for calculating Growth Rate is
Growth Rate (GR) is the total change in population size in a particular or given time.
T represents time (usually in years).

Complete answer: Nature has a limited amount of source to provide or it has some carrying capacity. Beyond a particular limit, nature cannot provide the source and the world population is growing at very fast (beyond the carrying capacity of nature) especially of China and India.
At present, the world population is increasing at a rate of around 1.8% per year or 75 million annually. In 1963, the world growth rate peaked at 2.2% and then decline to 1.1% annually in 2012. The population of a country increases due to illegal migration, early marriage, less death rate as medical facilities are increasing and improving, increase in birth rate, etc.

Additional information: In a 2004 long-term calculated report, the United Nations Population Division estimated the world population would peak at 9.22 billion in 2075.
After extending this maximum, it would decline slightly and then resume a slow increase, reaching a level of 8.97 billion by 2300, about the same as the projected 2050 figure.

So the correct answer is E. 1.8 %

Note: Population explosion is defined as large increase in population in small time. Moreover, the rapid increase in population in a small period of time.