Answer:
Evolution
Explanation:
Evolution is the change in habits, hereditary and physical characteristics of a species over various generations in response to environmental conditions. Evolution lead to adaptation, the nature selection of the fittest and elimination of remaining.
Evolution may produce variety and diversity in response to mutation, genetic drift and other genetic variation. These changes may pass to offspring and may express them more in one group of population.
Evolution also explain the unity among organisms by explaining their shared characteristics. This refers to their common ancestors.
The correct answer is a muscle tissue, more precisely cardiac muscle tissue. <span>Cardiac muscle tissue consists of individual cardiomyocytes (heart muscle cells) which are connected by intercalated discs to work as a single functional organ. The function of intercalated discs is to support synchronized contraction of cardiac muscle.</span>