C, pretty sure due to natural selection and theory of evolution
T cells. When HIV arrives in the lymph nodes – around 24 to 48 hours after exposure – they activate other immune cells, such as CD4 t-cells, HIV's primary target.
Answer:
The correct answer will be option-C.
Explanation:
Hypothalamus is a part of the brain which controls many important functions of the body by producing hormones.
When the amount of water gets reduced in the blood, it leads to a change in the osmolarity which can be easily detected by the osmorecpetors present in the neurons of the hypothalamus.
In response, neurons secrete Anti-diuretic hormone in the blood which acts in the tubules of the kidney where they help in re-absorption of the water from the body.
Thus, Option-C is the correct answer.
People believed that zebras were white animals with black stripes, since some zebras have white underbellies. Embryological evidence, however, shows that the animal's background color is black and the white stripes and bellies are additions.
The correct option is "D", "<span>The density of seawater".
As you are measuring the</span><span> amount of mass in a volume of water and if we look at the definition of density, it is the mass per unit volume.
D = m/v
where m is the mass of an object and v is the volume.
Thus, d is the correct option.</span>
