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.
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Question: Problem: after giving a discount of rs. 45 the shopkeeper gets a loss of 10 %, if the cost price is rs. 180. find the markup % ?
Options: a. 0.21, b. 0.2, c. 0.17, d. 0.21, e. 0.15

Answer: e

Question: Problem: what is the units digit of ( 3 ^ 13 ) ( 4 ^ 13 ) ?
Options: a. 2, b. 4, c. 6, d. 7, e. 8

Answer: a

Question: Problem: total 30 cows 10 cow gives each 2 liter milk 10 cow gives each 3 / 4 liter milk 10 cow gives each 1 / 4 liter milk this is split into 3 son per each 10 cows & 10 liter milk how ?
Options: a. 10, b. 12, c. 15, d. 16, e. 18

Answer:
a