The 2-week period of prenatal development that begins at conception is the stage; the period of prenatal development that lasts from the second week until about the eighth week is the stage. embryonic; fetal zygotal; fetal germinal; embryonic fetal; embryonic

Development occurs rapidly during prenatal period, which is the time between conception and birth. there are three stages in this period: germinal stage, embryonic stage, and the fetal stage.germinal stage is the 2-week period of prenatal development that begins at conception. conception occurs when a sperm cell and an egg cell combines to form a zygote and about thirty-six hours after conception, the zygote begins to divide briefly. the resulting ball of cells moves along the mother's fallopian tube to the uterus. around seven days after conception, the ball of cells starts to become embedded in the wall of the uterus and this process is called implantation and take about a week to complete. furthermore, there would be the formation of placenta.embryonic stage is the period of prenatal development that lasts from the second week until about eight week. the developing ball of cells is now called embryo. this is the most crucial stage because the major organs are formed and the embryo becomes very fragile.fetal stage is the period of prenatal development that lasts from the ninth week until birth. about a month into this stage, the sex organs of the fetus begin to form. the fetus quickly grows as bones and muscles forms, and it begins to move inside the uterus. the organ system develop further and start to function. the brain increases rapidly in size, an insulating layer fat forms under the skin, and the respiratory and digestive systems starts to work independently  during the last three months.

The right answer is b hydrogen bonds!

4, two dominant and two recessive