At the opening of a trading day at a certain stock exchange, the price per share of stock M was $25. If the price per share of stock M was $28 at the closing of the day, what was the percent increase in the price per share of stock M for that day? Options:
A) 1.4 %  B) 5.9 %  C) 12 %  D) 12.5 %  E) 23.6 %

Rationale: "opening = 25 closing = 28 rise in price = 3 so , percent increase = 3 / 25 * 100 = 12 answer : c"
Answer: C