The area of South America is approximately 1.78 × 107 square kilometers. Its population is approximately 3.50 × 108 people. What is the approximate population density (people per square kilometer) of South America? Write your answer in standard form. If necessary, round your answer to the nearest hundredth.
A: 19.66 people/km^2
B: 1.97 × 10^15 people/km2
C: 5.09 people/km^2
D: 1.97 × 10^1 people/km^2