• In a male sterile plant, the anthers or pollen grains are non-viable, aborted, or physically absent (sterile pollen), preventing fertilization on any receptive flower.
• In contrast, a self-incompatible plant produces fully viable and fertile pollen grains; however, they cannot fertilize their own pistil due to physiological or biochemical self-recognition barriers, while retaining the ability to fertilize other compatible plants.
• Both male sterile and self-incompatible plants have normal, fertile ovaries.
• Therefore, male sterile plants differ in having sterile pollen (Option 2).

• Genetic variation in a crop population is heavily determined by its reproductive and mating system.
• Maize (Zea mays) is a strictly cross-pollinated (allogamous), monoecious species with over 95% outcrossing driven by wind pollination (anemophily), maintaining vast heterozygosity and open genetic reassortment.
• Conversely, rice and groundnut are predominantly self-pollinated (>99% autogamous) forming uniform homozygous lines, while sorghum is often cross-pollinated (5-15%).
• Therefore, Maize exhibits the highest chance of genetic variation (Option 3).

Analysis of Golden Rice biofortification:

• Beta carotene: Golden Rice was genetically engineered with phytoene synthase (psy) and carotene desaturase (crtI) genes to synthesize \(\beta\)-carotene in the grain endosperm, giving it a characteristic yellow-golden color and serving as a dietary provitamin A precursor.
• Alfa carotene: Minor isomer with half the provitamin A activity.
• Gamma carotene: Intermediate carotenoid.
• Zeta carotene: Intermediate precursor in the carotene biosynthesis pathway.