The pathway of RNA interference is a result of double stranded DNA entering a eukaryotic cell.

a. siRNA
b. miRNA

siRNA.

Explanation:

The RNA interference may be defined as the evolutionary conserved mechanism that helps in the gene regulation by the silencing of the small RNA molecules. Two main types are  siRNA and miRNA.

The siRNA (small interference RNA) is involved in the protection of the cell by destroying the exogenous ds DNA of the cell. The DICER  enzyme plays an important role in the processing of the small interference RNA and the guide strand of RNA is involved in the gene silencing.

Thus, the answer is option (a).

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

the correct answer is sex-linked recessive.

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