What ratio of people live on an income of $1.25 per day? 

A)  one in every nine people on the planet 
B)  one in every seven people on the planet 
C)  one in every five people on the planet 
D)  one in every three people on the planet

Income

Money received, especially on a regular basis, for work or through investments, vital for determining an individual's or household's economic status.

People

Human beings collectively, often referred to in the context of society, communities, or demographics.

Planet

A celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, not massive enough to cause thermonuclear fusion, and has cleared its neighboring region of planetesimals.