I don't know the real answer because you didn't attach the choices, but Adenine (A) is always paired with Thymine(T) and Guanine (G) is always paired with Cytosine (C).
Organism, population, community, ecosystem, biosphere
It is in vitro fertilization (IVF).
IVF is a type of assisted reproductive technology used for infertility treatment. It includes the steps like removing an ovum from the woman's ovaries, fertilisation (sperm cell from is injected using a microscopic needle, directly into each harvested ovum from the woman) outside the body, embryo transfer to the same or another woman's uterus after a few days.