Identical twins come from a single egg that split into two embryos, and fraternal twins are from separate fertiized eggs. Also, identical twins must be of the same sex and the sexes are equally likely, and sexes of fraternal twins are equally likely. Use the data table to complete parts (a) and (b) below. a. After having a sonogram, a pregnant woman learns that she will have twins. What is the probability that she will have identical twins? The probability is (Type an integer or a simplified fraction.)