Answer:
Replacement rate
Explanation:
In biology, replacement level or replacement rate refers to the amount number of offspring required to be produced to keep the level of population at a stable state without causing it to much decease.
Scientists use the replacement rate of plant and animal specie to assess the rate at which the population is reproducing at a stable level or are at some threshold zone and need to be taken care of.
Here in question, we see that some specific properties of mustard plants are focused that, plant survives only one month during which it produces 50 flowers. each flower produces a fruit containing 20 seeds.
It clearly do not depicts the population size of mustard plant, or niche or fitness, it just describe the replacement rate that how many offspring does mustard plant produce to keep its population at a stable or steady state without being getting into a danger of extinction.
Hope it help!