Solution:(c) Mother said, "When we pluck a flower it dies so we should let it beautify the world as long as it lives." (Correct)(a) Mother says, "When we pluck a flower it dies so we should let it beautify the world as long as it lives." (Incorrect Reporting Verb)
(b) Mother said, "When we pluck a flower it dies so you should let it beautify the world as long as it lived." (Incorrect Verb)
(d) Mother said, "When we plucked a flower it died so we should let it beautify the world as long as it lived." (Incorrect Verb)