Extreme poverty is often defined as living on less than US$1 per day how has extreme poverty changed between 1981 and 2004 ?

A. stayed the same around 1.5 billion people
B. rose from 1.5 billion people to 3 billion
C. fell form 1.5 billion people to 1 billion
D. rose from 1.5 billion people to 2.5 billion