Parasitic infections are a primary cause of in many regions of the globe.

Parasitic infections are a primary cause of iron-deficiency anemia in many regions of the globe.
As the name itself says, iron-deficiency anemia is caused by a lack of iron in a person's blood, meaning that there are not enough red blood cells, leading to tiredness, weakness, shortness of breath, paleness, etc. Parasites increase the risk of anemia.

Idk i think the answer choice is number 1