Amelia has a coin that lands on heads with probability \dfrac{1}{3}, and Blaine has a coin that lands on heads with probability \dfrac{2}{5}. Amelia and Blaine alternately toss their coins until someone gets a head; the first one to get a head wins. All coin tosses are independent. Amelia goes first. The probability that Amelia wins is \dfrac{p}{q}, where p and q are relatively prime positive integers. What is q-p ?
Answer Choices
A. 1
B. 2
C. 3
D. 4
E. 5