Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[EX Q]: Problem: an optometrist charges $ 150 per pair for soft contact lenses and $ 85 per pair for hard contact lenses. last week she sold 5 more pairs of soft lenses than hard lenses. if her total sales for pairs of contact lenses last week were $ 1,220, what was the total number of pairs of contact lenses that she sold ?
Options: a. 9, b. 13, c. 15, d. 17, e. 19
[EX A]: a

[EX Q]: Problem: mr. loyd wants to fence his square shaped land of 120 sqft each side. if a pole is laid every 12 ft how many poles do he need ?
Options: a. 20, b. 30, c. 40, d. 50, e. 60
[EX A]: c

[EX Q]: Problem: a survey of n people in the town of eros found that 50 % of them preferred brand a. another survey of 125 people in the town of angie found that 60 % preferred brand a. in total, 55 % of all the people surveyed together preferred brand a. what is the total number of people surveyed ?
Options: a. 50, b. 100, c. 150, d. 200, e. 250
[EX A]:
e