We know as the first trimester of the pregnancy the period from conception to the 12 weeks of pregnancy.
Around 24 hours after the fertilization, the zygote becomes a blastocyst, which implants into the uterine wall. Then it becomes an embryo and during this stage, the placenta and umbilical cord are also formed.
The embryo becomes a fetus around 8 weeks after conception, and by this stage, fingers, eyes, mouth, and ears begin to be recognizable.
Of the options, the one which better aligns with the events of the first trimester is A. The placenta attaches to the mother and nourished the growing fetus.