Answer
B - I and III only
Work Step by Step
Small habitats have increased edge area, which can be a problem as it introduces species to other species that would not have normally encountered each other in an ecosystem. It also requires that species have a means of accessing other individuals of the species by means of corridors between the protected habitats in order to 'rescue' other populations and preserve genetic diversity.
II is incorrect as the increased dispersal of populations is not a problem of protecting small habitats; in fact, it's a benefit as a species is more likely to survive a natural disaster or disease if it occupies many different areas.
Therefore, I and III are correct.