The Aral Sea had witnessed a significant decline in its waters over the past half a century and the lake is on the verge of drying out totally and be wiped forever from the face of the Earth. This is happening due to a former Soviet policy were the waters of the lakes were overused for irrigation and bigger amount of water from the lake was taken out of it than what it gets by its tributaries. The water from the lake has mostly been used for the cotton plantations that are very high demanding on water. And even though the Soviet Union is long gone, the same policies continued to be practiced after its fall, so now we only have a pale shadow of what was once one of the biggest and most beautiful lakes in the world.
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).
