According to the Small-Population Approach, What Would Be the Best

According to the small-population approach, what would be the best strategy for saving a population from extirpation?

A) determining the minimum viable population size by taking into account the effective population size
B) establishing a nature reserve to protect its habitat
C) introducing individuals from other populations to increase genetic variation
D) determining and remedying the cause of its decline
E) reducing the population size of its predators and competitors