The Type O blood group is commonly called as universal donor because any blood group can receive the O blood group. The blood group O has no antigen. Due to the absence of antigen it doesn't agglutinate when come in contact with other blood groups in the plasma.
The agglutination reaction happens when opposite antigen and antibody reacts with each other. e.g.- Blood group A contains antigen A and antibody b and the blood group B contains antigen B and antibody a. Agglutination reaction occurs when the antigen A reacts with antibody a. As O blood group has no antigen, agglutination reaction doesn't occur.
There should be options for this question. I manged to find them elsewhere. They are:
A) the period during which tremendous growth occurs and the organs continue to develop and become functional
B) the period during which the umbilical cord develops
C) the period during which the major organs and structures of the organism first develop
D) the period during which the zygote moves down to the uterus and begins to implant in the lining
The correct answer is C. The embryonic period is the period during which the major organs and structures of the organism first develop. The embryonic period lasts from implantation of the egg in the uterus until about 8 weeks from the time of conception. It is the second major stage of prenatal development, prior to embryonic is the germinal stage and lastly is the fetal stage.
Answer::::::::::::::::::::C
Because good researchers rely on first hand account or better said primary evidence. The reason why they rely on primary evidence is because it is usually the most reliable. Much more so than secondary or even tertiary evidence. This enables them to understand the history of a certain topic better.
