In the picture attached to this question, the two diagrams above did not show very well but I believe that the first diagram contain four dots, which means that the correct option is A. Carbon has six electrons, that is why 6 is its atomic number is 6 . In writing electronic configuration, two electrons are usually placed in the most inner shell while the other shells will have 8 electrons each. In the case of carbon which has 6 electrons, only four will remain after 2 electron has been put in its inner shell. Therefore the number of electron in its outermost shell will be four.
