IMPORTANT PLEASE HELP!!
The world's population has grown at an average rate of 1.9 percent per year since 1945. There were approximately 4 billion people in the world in 1975. Which function represents the world's population P, in billions of people, t years since 1975? (1 billion = 1,000,000,000)
A. P(t)=1.19t+4
B. P(t)=1.019t+4
C. P(t)=4(1.9)^t
D. P(t)= 4(1.019)^t