The answer of this question is genes
The early immune response to HIV-1 infection is likely to be an important factor in determining the clinical course of disease. Recent data indicate that the HIV-1 quasispecies that arise following a mucosal infection are usually derived from a single transmitted virus. Moreover, the finding that the first effective immune responses drive the selection of virus escape mutations provides insight into the earliest immune responses against the transmitted virus and their contributions to the control of acute viraemia. Strong innate and adaptive immune responses occur subsequently but they are too late to eliminate the infection. In this Review, we discuss recent studies on the kinetics and quality of early immune responses to HIV-1 and their implications for developing a successful preventive HIV-1 vaccine.
Answer:
D. anything in the atmosphere.
Explanation:
The presence of hydrogen bond is one factor that explains the fact that ice floats over water because it has less density.
Due to this, rivers and lakes freeze from the surface whereas it is in liquid state at the bottom which allows the sea animals to survive even in colder temperatures.
Water makes up at least 70% of earth and 65% of our bodies and this property of water is essential for our lives as it maintains the survival.
