Read the following excerpt from a student essay. How can the writer best improve his or her ideas and development?
An elephant's trunk has many purposes, including breathing, smelling, drinking, lifting, and communicating. It contains about one hundred thousand different muscles. Elephants have a very long gestation period: a female is pregnant for nearly twenty-two months before giving birth. Newborn calves weigh as much as two hundred pounds. Sadly, thousands of elephants are killed every year for their ivory tusks. Even though the ivory trade is illegal, it has not been completely stopped. As a result, elephants are endangered.
A. by including more details
B. by clearly stating the main idea
C. by focusing on one main idea
Pick the correct answer from the listed options and provide the letter of the selected option.

C