A superficial person is one never thinking about things that are serious or important. For example, "He's fun to be with, but he's very superficial". Hence, Option A is correct. Among the rest of the options, superstitious means having or showing a belief in superstitions, superfluous means unnecessary, especially through being more than enough, supernatural means attributed to some force beyond scientific understanding or the laws of nature. These options do not express this meaning, hence incorrect.