Which of the following is in the correct order of the three periods in prenatal development from conception to birth? group of answer choices
a. gestational, germinal, postnatal
b. germinal, embryonic, fetal
c. preterm, germinal, postterm
d. fertile, embryonic, postterm

b.Germinal, embryonic, fetal

Explanation:

The period from conception to birth generally includes the order that is germinal, embryonic and fatal.

Germinal period: It begins with the rapid cell division and differentiation of the blastocyst which is a cell mass acts as a precursor of new life. The germinal period last for 2 weeks.

Embryonic period: This period lasts for 8-10 weeks. In this period a process called as gastrulation occurs in which the three layers called as germ layers develop. The ectoderm is the outer layer, the mesoderm is the middle layer and the endoderm is the inner layer. Each germ layer differentiate into different structures.  

Fetal period: It is the final stage of development of the fetus. It last for 10-40 weeks of pregnancy. It initiate from the embryonic period till the birth of the full term fetus. It involves the development and specializing of structures. Organ system of the fetus develops in this stage.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.