The correct answer is option c. It is projected to increase steadily.
Explanation;
The current population of the world is estimated as more than 7.2 billion. The population is projected to be increased by 1 billion and has also estimated to cross 9.6 billion by the end of the year 2050. So, the population is increasing at a steady rate. In the total population increase, the contribution of the developing countries would be more.