instruction:
Given a scientific question, generate a correct answer to it.
question:
Which theory describes the benzene molecule and other planar aromatic hydrocarbon molecules as hexagonal rings of sp2-hybridized carbon atoms with the unhybridized p orbital of each carbon atom perpendicular to the plane of the ring?
answer:
valence bond theory

question:
Two kinds of sex hormones are of particular importance in females: progesterone, which prepares the uterus for pregnancy and prevents the further release of eggs from the ovaries during pregnancy, and the estrogens, which are mainly responsible for the development of female secondary sexual characteristics, such as breast development and increased deposition of this?
answer:
fat

question:
E. coli uses how many enzymes to take up and metabolize lactose?
answer:
3