How do I solve stoichiometry problems? Please I need help with at least one of these stoichiometry problems with work and steps so I understand better. Thank you!

C is the correct answer.a buffer reacts with the added acid or base which can produce H+ or hydroxide ion,or a kind of removing H+ or hydroxide added to solution.remember that buffers don't prevent additional acid or base from reacting,they react with the additional themselves.the A and D are completely wrong.