Awoman's pregnancy has been uneventful, and she has gained 25 lb (11.3 kg). at term her hemoglobin level is 10.6 g/dl (106 mmol/l) and her hematocrit is 31%. what is the physiologic reason for these hemoglobin and hematocrit levels?

Hemoglobin is a protein in red blood cells that carries oxygen throughout the body.

It indicates anemia, in women, when hemoglobin levels are lower than 12 grams per deciliter. 

It's common to happen in pregnant women.

Hematocrit is also lower that normal  ( 36 to 48% for women). Hematocrit is the fraction of blood that is made up of red blood cells. It's important to be measure when suspecting of anemia.

the correct answer is - d. china has a large and growing population.

the fact that china has a large (the biggest) population, and it is still growing, doesn't hinder the agriculture production in the country. in fact, it can for increased production in the agriculture, since there's more labor force, as well the sheer mass of people produces lots of scientists that come up with new inventions as to how to improve this sector. nice example is the inner mongolia region in china, in general dominated by the gobi desert, but few scientist came up with a nice idea as to how to make the region productive by using plants that are very resistant to droughts, so lots of people have been employed, and the region is becoming greener and greener each year, and the production of food in this region is also increasing.