In an area of erratic rainfall, a biologist found that grass plants with alleles for curled leaves reproduced better in dry years, and grass plants with alleles for flat leaves reproduced better in wet years. This situation would lead to the following outcome: [a] Causes Genetic drift in the grass population. [b] Preserves genetic variation in the grass population. [c] Leads to Stabilizing selection in the grass population. [d] Leads to Uniformity in the grass population.

The correct answer is: [b].

Explanation:

According to the question, the area where the grass plant grows is characterized by erratic rainfall. This means that in the region both dry and wet climate persists. Hence, it is necessary for the grass plants to adapt themselves to both the type of climate, that is, dry and wet. In the dry climate, the grass plants which produce curled leaves to prevent excess water loss due to transpiration survives. In the wet climate, the grass plants which produce flat leaves to increase food production due to the availability of enough water and also for removing excess water by the process of transpiration, survives. The contrasting variation in climate which persists in the area in different time intervals prevents the complete reproductive dominance or success of one variety of grass plant (curled leaved) over the other (flat leaves). Hence, both the curled leaf and flat leaved variety of grass plant exists in the area and the population of either increase or decrease depending on the climatic condition of the area.