Consider the following statements. (a) Tendency of two or more genes of the same chromosomes to remain together during the process of inheritance is known as crossing over. (b) Homo-gametic is the condition in which there are two different types of gametes formed. (c) In the process of crossing over, the crossing over occurs at two points in the same chromosome pair. (d) Allele frequency is a measure of the relative frequency of an allele on a genetic locus in a population. Which of the above statements is/are correct?