Took me a good 15 seconds to realize what the difference was.
C.) is correct if you have a word that ends with s and you need to make it possessive you use a apostrophe after the s.
Example: You guys' chairs look bad.
Answer is C
When writing for a very young audience, they should avoid use of complex words.
The world population increased throughout 1950 to 2000 after the industrial revolution and wars. The population in 1950 started as 6.9 billion people. In 2000 the population grew to be 9.6 billion people. After the wars people were happy to see their family’s and started growing their family bigger. During this period of time the population rapidly increased.
