Question

when thinking about the force of natural selection, its important to remember its three key requirements.
there must be mutliple versions of a single trait (such as beak size) in the population
the more fit organisms have a greater chance to reproduce
and the trait must be heritable.
take a look at the various tortoises on hood island. some of the tortoises have long necks and are well suited to eat from tall plants that grow on the island. those with short necks, have a lower chance of survival. the neck length trait is genetic.
based on this evidence, would natural selection act on these tortoises?
yes, because tall necks is the only trait in the population of tortoises so it is the most favorable.
no, because the pressure to eat doesnt affect the survival of the tortoises.
yes because neck length is genetic, favored by the environment and leads to enhanced survival and reproduction.
no, because neck length is not genetic.
the data provided in this question are not enough to make a conclusion.

Explanation:

Natural selection requires trait variation, differential reproduction based on fitness, and heritability. The tortoises have neck - length variation (long and short necks), long - necked tortoises are more fit (better access to food, higher survival), and neck length is genetic (heritable).

Answer:

Yes because neck length is genetic, favored by the environment and leads to enhanced survival and reproduction.