In order to decrease the genetic diversity of a population, you would need to
add individuals to a population
only let individuals breed with other individuals that have very different characteristics
increase a population's territory
remove individuals from a population

it's c. (to reduce the greenhouse effect/carbon gasses)

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

those characteristics are cellular organization, reproduction, metabolism, homeostasis, heredity, response to stimuli, growth and development, and adaptation through evolution. some things, such as a virus, demonstrate only a few of these characteristics and are, therefore, not alive