Help me please i have no idea how to do this

The correct answer is A.

In geometry, a set of points in space are coplanar if there exists a geometric plane that contains them all. For example, three points are always coplanar, and if the points are distinct and non-collinear, the plane they determine is unique. In other words, to be coplanar, all points have to lie in the same plane. Point d is not in the plane, therefore all points except d, are non coplanar.

Bis your answer. it only holds the decimal numerals

The answer is (a) 12-2(-1)(6)2(6)=12