6. 120 points] Answer the following questions and justify your answers. a) If X and Y are sequences that both begin with the character A, every longest common subsequence of X and Y begins with A. b) If X and Y are sequences that both end with the character A, some longest common subsequence of X and Y ends with A. 6. 120 points] Answer the following questions and justify your answers. a) If X and Y are sequences that both begin with the character A, every longest common subsequence of X and Y begins with A. b) If X and Y are sequences that both end with the character A, some longest common subsequence of X and Y ends with A