The reason why hybrid seeds have to be produced every year is

The correct option is: "hybrid vigour is not maintained in more than one generation as segregation of genes is initiated in the second generation"

Explanation:

1. Understanding Hybrid Seeds and Hybrid Vigour:
Hybrid seeds are produced by cross-pollinating two different inbred parent lines that possess distinct, desirable traits. The first-generation offspring ($F_1$ generation) typically displays superior characteristics compared to both parents—such as higher yield, better disease resistance, and greater vigor. This phenomenon of superior performance is known as hybrid vigour or heterosis.

2. The Genotypic Status of $F_1$ Hybrids:
The $F_1$ hybrid plants are highly heterozygous, meaning they carry different alleles for many genes. Because they are all genetically identical to each other in this heterozygous state, the crop grows uniformly and performs consistently across the field.

3. Why Hybrid Seeds Cannot Be Reused (The $F_2$ Generation):
If a farmer saves the seeds harvested from the $F_1$ hybrid crop and plants them the following year (producing the $F_2$ generation), Mendelian segregation of genes occurs. During meiosis and subsequent fertilization, the alleles that were combined in the $F_1$ hybrid separate (segregate) and recombine in various combinations. This genetic segregation leads to a wide variation in the offspring, where many plants lose the desirable combinations of traits that gave them their hybrid vigour. Consequently, the crop lacks uniformity, and the yield and quality drop significantly.

Therefore, to maintain high crop yield and quality, hybrid seeds must be produced afresh and purchased every year.