The earth’s population has increased by more than people in the last 100 years. a. 300 million b. 7 billion c. 6.9 billion d. 5 billion

the world's current population is 7.3 billion and the world population in 1915 was 1.8 billion. The increase over the past century is 7.3 billion - 1.8 billion = 5.5 billion. So, the correct answer would be "more than 5 billion" (option D).