Biotic potential or potential natality means
A. Natural increase of population under ideal/optimum conditions.
B. Potential of organism in a biome.
C. Number of organisms in a biome.
D. Species of maximum number in a population.

Hint: The highest quantity of a species in a particular area is referred to as biotic potential. The biotic and abiotic factors constitute the environment. The living organisms that include plants, animals and microorganisms like decomposers, bacteria etc. are called biotic factors and non-living factors i.e. rock, soil etc. are biotic factors.

Complete Answer:
- Biotic potential or potential natality means the natural increase of population under optimum/ideal conditions. The ratio of rate of birth to the total population of a place, is called as natality. Natality and mortality are the two opposite factors.
- The biotic potential is directly proportional to the fertility rate. The biotic and abiotic factors together constitute the biosphere.
- Natality refers to the rate of reproduction or birth per unit timed. It is an expression of the production by birth, hatching, germination or fission. Natality is calculated by birth rate or natality is the number of birth per unit time to the average population.
- Potential natality or reproductive natality is the upper limit to biotic potential in the absence of mortality. Survival potential is the reciprocal of mortality, because potential natality does not account for the number of gametes surviving. Survival potential is a necessary component of biotic potential.

Therefore, the correct option is (A) Natural increase of population under ideal/optimum conditions.

Note: Natality and mortality are two opposite factors which can cause confusion. The greater natality rate with lesser mortality rate will lead to increase in population whereas greater mortality and less natality rate will decrease the population.