Choose the word or phrase among A, B, C or D that best fits the blank space in the following passage 

 

Nearly 200 of the 1500 native plant species in Hawaii are at risk of going extinct in the near future because they have been (27) ____ to such low numbers. Approximately 90 percent of Hawaii's plants are found nowhere else in the world but they are (28) ____ by alien invasive species such as feral goats, pigs, rodents and non- (29) ____ plants.  The Hawaii Rare Plant Restoration Group is striving to (30) ____ the extinction of the 182 rare Hawaiian plants with fewer than 50 individuals remaining in the (31) ____. Since 1990, (32) ____ a result of their ‘Plant Extinction Prevention Program’, sixteen species have been brought into (33) ____ and three species have been reintroduced. Invasive weeds have been removed in key areas and fencing put up in order to (34) ____ plants in the wild.  In the future the Hawaii Rare Plant Restoration Program aims (35) ____ collecting genetic material from the remaining plants in the wild for storage as a safety net for the future. They also aim to manage wild populations and where possible reintroduce species into (36) ____.  Rewrite the following sentences so that the second ones have the same meaning as the given sentence 

Nearly 200 of the 1500 native plant species in Hawaii are at risk of going extinct in the near future because they have been (27) ____ to such low numbers.