Which of the following pair(s) of circles have l as a common external tangent? select all that apply. a and b a and c b and c

The picture in the attached figure  we know thatinternally tangent circles when two circles are tangent and one is inside the otherexternally tangent circles when two circles are tangent and next to each othersoin the problemcase (a and >   are  externally tangentcase (a and >   are  externally tangentcase (b and >   are internally  tangentthereforethe answer is  a and ba and c