18. Which of the following groups of numbers are all prime numbers?
A. 7, 17, 29, 49
B.2, 3, 5, 9
C. 2, 5, 15, 19
D. 3, 11, 23, 31

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .