Ahacker is trying to guess someone's password. the hacker knows (somehow) that the password is 12 characters long, and that each character is either a lowercase letter, (a, b, c, etc), an uppercase letter (a, b, c, etc) or a numerical digit (0, 1, 2, 3, 4, 5, 6, 7, 8, or 9). assume that the hacker makes random guesses.

3. parallelogram

step-by-step explanation:

we turn each of our sides into direction vectors

ab=b-a=(3 - 7, 1 - 0) = (-4, 1)

bc=c-b=(1,6)

cd=d-c=(4,-1)

da=a-d=(-1,-6)

we see how the opposite sides have negated direction vectors; this is characteristic of a parallelogram.   we have congruent sides ab=cd and bc=da with unequal lengths because 1^2+6^2 is different from (-4)^2+1^2.   so it's not a square or a rhombus.  

we check the dot product of direction vectors of adjacent sides.   we have

ab dot bc = -4(1) + 1(6) = 2

that's not zero so the sides are not perpendicular.   we've ruled out rectangle.

the direction vectors indicate two pairs of congruent parallel sides, so we choose parallelogram over trapezoid.

entering that problem on the tube might get you an answer