Determine the correctness or otherwise of the following assertion [a] and reason [r]: Assertion [a]: Aircraft directional static stability can be improved by moving the vertical tail rearward. Reason [r]: Moving the vertical tail rearward increases the moment arm from the tail aerodynamic center to the aircraft center of gravity.

• A. Both [a] and [r] are true and [r] is the correct reason for [a]
• B. Both [a] and [r] are true but [r] is not the correct reason for [a]
• C. Both [a] and [r] are false
• D. [a] is true and [r] is false