Boosts the immune system, regulates hormones, and produces hemoglobin.

potassium
water
calcium
iron

Iron boosts the immune system, regulates hormones, and produces hemoglobin.

Option D

Explanation:

The UCLA research team recently found a new hormone named erythroferrone. It controls the supply of iron that required to generate red blood cells (RBC). Iron is a vital functional component for haemoglobin, a molecule that carries oxygen all over the body.

Using mouse model, researchers found that this hormone was produced by the RBC progenitors in the bone marrow. It is to adapt iron supply to the needs of RBC production.

The hormone is significantly increased when RBC production is stimulated, for example after bleeding or in anaemia response. The hormone regulates the hepcidin, primary iron hormone, which controls the iron absorption from food intake and the iron distribution in body.

u

explanation:

answer: the correct answer for the fill in the blank is rods.

rods are the specialized photoreceptor cells that are present in the retina of human eye. they are responsible for vision in the night time ( also called scotopic vision). they have very low visual acuity and color distinguishing ability.

as they are responsible for vision in night time, therefore they are found predominantly in the nocturnal animals.