M=
or is it undefined?

Exact perimeters given coordinates are ugly, the sum of a bunch of square roots. A calculator approximation isn't so bad, especially when the choices are so far apart; we can just keep one decimal place.

There's only one rule in play, that the length of a segment with endpoints (a,b) and (c,d) is given by the Pythagorean Theorem as

It's going to be too boring for me to do more than one or two, so hopefully you'll learn how and do the rest yourself.

E(2,9),F(2,2),G(10,2)

Of course there's a shortcut when one of the coordinates between the endpoints is the same; then we can just skip the square root.

So an approximate perimeter of 7+8+10.6=25.6

First choice

One more, a quadrilateral

M(1,8), N(9,8), O(9,2), P(1,2)

No square roots needed for that one, which is apparently a rectangle, perimeter 8+6+8+6=28

Second choice

I leave the rest for you