You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

[Q]: Question: Triangle STV has sides ST = TV = 26, and SV = 20. What is the area?

 Option A: 160

 Option B: 180

 Option C: 200

 Option D: 220

 Option E: 240
[A]: Option E


[Q]: Question: X is able to do a piece of work in 8 days and Y can do the same work in 12 days. If they can work together for 3 days, what is the fraction of work left?

 Option A: 8/5

 Option B: 6/5

 Option C: 7/5

 Option D: 3/5

 Option E: 4/5
[A]: Option D


[Q]: Question: Each of seven different locks has a matching key. The keys are randomly reassigned to the locks. What is the probability that exactly two of the keys fit the locks to which they are reassigned?

 Option A: 1/8

 Option B: 1/6

 Option C: 1/49

 Option D: 3/8

 Option E: 1/2
[A]:
Option C