At the time of gamete formation, the two alleles of a gene separate from each other and pass into different gametes. It is called as

Correct option is B

The separation of the two alleles of a gene during gamete formation is a fundamental principle of inheritance. This principle states that each gamete receives only one allele of a gene pair. This phenomenon is known as the Law of Segregation.
Information booster: The Law of Segregation was proposed by Gregor Mendel based on his pea plant experiments. It explains why offspring inherit one allele from each parent for a particular trait. The law operates during meiosis, when homologous chromosomes separate. It forms the basis for understanding monohybrid crosses and genetic ratios.
Why other options are incorrect: (a) Lethal genes cause death in certain genetic combinations and are unrelated to allele separation. (c) Law of Independent assortment deals with the inheritance of different gene pairs. (d) None of these is incorrect because the law of segregation correctly explains the statement.