a. Which pair of circles shown above are externally tangent?

b. Which pair are internally tangent?

The figure is given.

Two circles are externally tangent if their intersection point is one and intersection of their interior is empty.

Now, we apply our concept that is-

Two circles are externally tangent if their intersection point is one and intersection of their interior is empty.

Therefore in figure (b) pair of circles are externally tangents as shown below.

Given figure has two internal tangents as shown below.

Therefore, the answer is $\left(b\right).$

The figure is given.

Two circles are externally tangent if their intersection point is one and intersection of their interior is not empty.

Now, we apply our concept that is-

Two circles are externally tangent if their intersection point is one and intersection of their interior is not empty.

Therefore in figure (b) pair of circles are internally tangents as shown below.

Therefore, the answer is $e.$