As seen from a distant planet, ships A and B fly toward each other, with ship A having a speed of $0.91c$. and ship B having a speed of $0.55c$. According to the pilot of ship A, how fast is ship B approaching?

• A. $0.24c$
• B. $0.72c$
• C. $0.99c$
• D. $c$
• E. $2.9c$
• F. $0.97c$