The correct answers are
A. In the Hebrew tradition of Gematria, where the numerical value of words is considered for interpretation, chalav, meaning milk, has a value of 40, which corresponds with the number of days Moses remained on Mt. Sinai when receiving the Torah.
and
B. Shavuot is referenced in the Torah portion Pinchas, in Chapter 28, verse 26, which reads “In the day of the first fruits, when ye bring a new meal-offering unto the Lord in your feast of weeks, ye shall have a holy convocation.” In Hebrew, this sentence includes the phrase “Chadasha L'Hashem V’Shavuoteichem.” The first letters of those words–Chet, Lamed, Vet–spell chalav, the Hebrew word for milk.
and
E. When baby Moses was rescued from the river by Pharaoh’s daughter, he needed to be fed. Moses refused to suckle from the Egyptian wet nurses that Pharaoh’s daughter hired. Only when the Hebrew slave Yocheved, who was actually Moses’s mother, was chosen for that task, would he nurse. Eating dairy on Shavuot commemorates Moses’s holding out for his own mother’s milk.