From my point of view the answer should be b,d.

I think the qstn is not very clear in what it says so. What I understand is the Polygon object has many vertices (x1,y1) , (x2,y2).....(xn,yn) and it has a Color as a member var using which the Polygon is drawn. It also implements an interface drawable (it may be the name of the interface).This info can be stored in many ways in a Vector. The storing and retriving mechanism must be compatible. For color, A new Color object may be created and added to the Vector object. For the vertices there can be int[n][2] array which has the (x,y) coordinates. For storing the vertices we may have to create an int[n][2] where n is total no of vertices to be drawn. In this case the 3rd answer comes as just a var name 'vertice' not a Type. So we CAN use this vertice as a var name. Otherwise there may be a class named 'vertice' which has x,y as instance member vars. In that case, to store the vertices of the Polygon we may have to create an array of type 'vertice' and add this array to the Vector object. Or we can directly create this 'vertice' class type object and add to Vector object without creating as an array as a member var. Since the qstn asks about member var of the Polygon we have to ignore the last one which i just described. Generally we use CAPITALIZED FIRST letter for class Types and LOWERCASE first letter for var/methodNames etc. If we see in that angle the 3rd ans 'vertice' more likely a member var name which we CAN USE for declare the members.
This is my thought.
Others can add to this.
regds
maha anna

A Polygon is Drawable.Polygon has several vertices which are stored in a vector,Color for filling and a flag which is of type boolean.

and hence the memeber variables used in Class Polygon are of type Color, Vector and boolean

So, the answer is b and d.