(A) Copying of maternal genes to produce maternal messenger RNA’s

(B) Sythesis of proteins called histones

(C) Division of a cell into its nucleus and the cytoplasm

(D) Determination of the egg cell’s potential for division

(E) Generation of all of a cell’s morphogenetic determinants

In paragrah 3, " When the egg is fertilized,the substances become active and, presumably, govern the behavior of the genes they interact with.". Then, in paragraph 4, "The substances that Gross studied are maternal messenger RNA’s" ---> "these particular RNA’s

direct, in large part, the synthesis of histones"

So it's clear to see the path: egg fertilized --> substances(RNA) activated --> synthesis of histones directed by RNA

From the above, we can infer that B is the correct answer.