Final answer:
Crop rotation is the practice that helps maintain food diversity by improving soil fertility, introducing pest resistances, and diversifying crops, which contrasts with monoculture that depletes soil nutrients and fosters genetic uniformity.
Step-by-step explanation:
The agricultural practice that helps to maintain food diversity is b) Crop rotation. This practice involves alternating the type of crops grown in a particular area each season or year. Crop rotation can contribute to soil fertility, diversify crops, and reduce pesticide costs by naturally breaking the life cycle of weeds, insects, and diseases. It also introduces resistance to pests and extends the range of usable land. On the contrary, monoculture, which is growing the same crop repeatedly, can deplete soil nutrients and may attract plant pests, hence reducing biodiversity and promoting genetic homogeneity. Moreover, diverse varieties of crops surrounded by a diverse ecosystem are more likely to survive catastrophic events and contribute to agricultural sustainability.