Marc was a participant in a clinical study to determine how much niacin cures pellagra, the niacin deficiency disease. During the study, he consumed only a formula diet that was deficient in niacin. After developing pellagra, he was given 2 mg of niacin a day for 2 weeks, but he still suffered from the disease, so the scientists added 2 mg of the vitamin to Marc's formula. By the beginning of the 5th week of the study, the researchers noticed that Marc's signs and symptoms were greatly improved. At the end of the 5th week, he was feeling fine. The researchers concluded that:

explanation:

they can be good for the ecosystem

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

answer; i believe the correct answer is (data); /// good luck

the index of refraction of the second medium is higher. i just took the test trust me !