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: the population of a town increases 25 % and 40 % respectively in two consecutive years. after the growth the present population of the town is 1750. then what is the population of the town 2 years ago ?
Options: a. a. 750, b. b. 800, c. c. 850, d. d. 900, e. e. 950
[EX A]: b

[EX Q]: Problem: if the price of a certain computer increased 30 percent from b dollars to 351 dollars, then 2 b =
Options: a. 540, b. 570, c. 619, d. 649, e. 700
[EX A]: a

[EX Q]: Problem: a feed store sells two varieties of birdseed: brand a, which is 40 % millet and 60 % sunflower, and brand b, which is 65 % millet and 35 % safflower. if a customer purchases a mix of the two types of birdseed that is 50 % millet, what percent of the mix is brand b ?
Options: a. 40 %, b. 45 %, c. 50 %, d. 60 %, e. 55 %
[EX A]:
a