The best and most correct answer among the choices provided by your question is the first choice or letter A.<span>A biological agent that cannot reproduce on its own is a VIRUS.
</span>A virus<span> is a small infectious agent that replicates only inside the living cells of other organisms. </span> I hope my answer has come to your help. Thank you for posting your question here in Brainly.
A biological agent that cannot reproduce on its own is a VIRUS. A virus is a minute infectious agent that replicates just inside the living cells of different organisms, It typically consists of a nucleic acid molecule in a protein coat, it is extremely small to be viewed by light microscopy, and is able to multiply only among the living cells of a host.
Sickle-cell anemia is caused by a point mutation in the β-globin chain of hemoglobin, causing the hydrophilic amino acid glutamic acid to be replaced with the hydrophobic<span> amino acid valine at the sixth position.</span>
