What would be a reasonable biological scenario for how speciation occurred why speciation has yet to occur
but appears to progressing, or why speciation has not occurred and why it will not?

d. the weight of the book

i would say it is

in a chemical reaction, the atoms and molecules produced by the reaction are called products. no new atoms are created, and no atoms are destroyed. in a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.