Explanation

Genetic male sterility in plants is typically controlled by non-allelic genes (cytoplasmic-nuclear interaction) or nuclear restorer genes, but the classic definition often emphasizes cytoplasmic factors interacting with nuclear genes. However, strictly speaking, GMS is often associated with cytoplasmic male sterility (CMS) which involves mitochondrial DNA, not just nuclear genes. But looking at standard agricultural genetics MCQs, 'Non alleleic genes' or 'Cytoplasmic genes' are common answers. Let's re-evaluate. Actually, Genetic Male Sterility (GMS) is specifically controlled by nuclear genes, whereas Cytoplasmic Male Sterility (CMS) is controlled by cytoplasmic genes. The question asks for 'Genetic male sterility'. GMS is indeed controlled by nuclear genes. So C might be correct. Wait, some sources say GMS is controlled by recessive nuclear genes. Others distinguish between CMS (cytoplasmic) and GMS (nuclear). If the question implies the general category of genetic control excluding cytoplasmic, then nuclear genes is correct. However, in many Pakistani exam contexts (like CSS/FPSC), they might refer to 'Non-allelic' interaction for heterosis or sterility. Let's check standard texts. GMS = Nuclear genes. CMS = Cytoplasmic genes. So C is likely correct. But wait, sometimes 'Genetic male sterility' is used broadly. If the current answer is C, and GMS is nuclear, then C is correct. I will stick with C being correct for GMS specifically.