Select the best description of adaptations, below.

a
A nonrandom mechanism of evolution in which the fittest organisms survive and leave the most offspring
b
An inherited modification of structure or function that allows an organism to survive and reproduce in its environment
c
The process of breeding only livestock or crops with desirable characteristics to increase the frequency of those characteristics in the offspring
d
The idea that all organisms share an ancient common ancestor

b

An inherited modification of structure or function that allows an organism to survive and reproduce in its environment.

Explanation:

Adaptation helps an organism to become better suited to survive and reproduce in its environment. It is change in an organism's structure or behavior.

Change in physical features of an organism is considered as structural adaptation. Example- fur in bear

Change in the way an organism does things to survive is called behavioral adaptation. Example- bird calls and migration from one place to another.

Adaptation is an essential feature that helps an organism to better servive in the environment. In case, an organism fails to adapt to changes in its environment, its immune system becomes weak and fails to work. This threatens its life and it becomes ill. This may also result in its death.

An inherited modification of structure or function that allows an organism to survive and reproduce in its environment is the best description of adaptation.

Explanation:

Adaptation is the process in which a favorable or beneficial trait is passed on to organism and ability to survive in the environment. Offspring are produced with beneficial characters to survive.

The traits expressed (phenotype) are in large number of variations. These traits which are beneficial for the organism to survive in the environment it lives increases. It means the allele frequency of the useful trait increases in the population. The population having received the trait will survive and evolve for better adaptations.

the answer to your question is b