Answer:
Option D, all of the above
Step-by-step explanation:
All the demographic components are very essential for balancing the population of any species be it human or animals. The major components of demography are age, sex, average age of mating, average number of children per family, etc.
All these components of demography/population are affected by environmental conditions. In favorable environmental condition, species/organism mates with each other to produce healthy offspring which could result into a well distributed age structure of the population thereby balancing the population.
Option D, All of the above