Q: 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.
Question: A shop sells bicycles and tricycles. In total there are 10 cycles (cycles include both bicycles and tricycles) and 21 wheels. Determine how many of each there are, if a bicycle has two wheels and a tricycle has three wheels.

Option A: b=9,t=1

Option B: b=7,t=3

Option C: b=6,t=2

Option D: b=2,t=5

Option E: b=6,t=4
A:
Option A