Notice that the integers are randomly generated from 0 to 7 (that is eight digits randomly generated). We are asked to consider success the extraction of a 0, 1, 2, or 3 (4 of these randomly generated digits)
Therefore the chances of success can be estimated as: 4 / 8 = 1/2 = 0.5 = 50%
which agrees with the last option (D) in the provided list.