The correct option is D Once in 50-100 yrs
Some plants are monocarpic i.e. they flower only once in their lifetime. Bamboo (Bambusa) produces flowers only after 50-100 years, produce large number of fruits once in their lifetime and die. Another such example is the Neelakuranji (Strobilanthus kunthiana) which flowers synchronously after every 12 years, set seeds and die.