Which is part of the theory of evolution by natural selection?
o
a. only the best-adapted animals in a population survive.
b. evolution can only cause small changes to a species.
c. adaptations cannot be passed along to the next generation.
) d. animals that survive cannot pass along their adaptations.

The correct answer is: A. Only the best-adapted animals in a population survive.

Explanation:

Natural Selection is the process by which the individuals of a species which has the potential to sustain and survive in adverse or changing environment gets a survival advantage over those individuals which are unable to adapt themselves to altered environmental conditions.As the less potent individuals die in altered environmental conditions the  adaptable individuals escapes competition with them for natural resources.Evolution causes species to alter their characteristics depending upon the demand of the conditions. These changes can vary, can be less or drastic.Animals pass all the newly adapted traits to the successive generations either as genetic traits or as acquired traits, as this is necessary for the offspring to survive in the altered environment.Natural selection is best defined as "the survival of the fittest".