Final answer:
The number of people living in absolute poverty, defined as living on less than $1.90 a day, is closest to one and a half billion. This reflects the widespread extent of global poverty, particularly in populous countries such as China, India, Nigeria, and Egypt.
Step-by-step explanation:
The number of people in the world who are absolutely poor is closest to one and a half billion. Absolute poverty is defined by the World Bank as living on less than $1.90 a day. According to the latest data, approximately 689 million people live on less than $1.90 a day, whereas close to 3 billion people live on less than $2.50 a day.
With China, India, Nigeria, and Egypt having large shares of their populations living under these amounts, the extent of poverty is significant.
It is also important to note that while someone might live on a little more than $1.90 a day, they might still be facing severe poverty, highlighting the vulnerability of people just above the extreme poverty line defined by international standards.
Thus, the most accurate option that resembles the condition described as 'absolute poverty' in the question is (c) one and a half billion.