A(3, 2), B(6, 6), C(2, 9) and D(-1, 5) are taken in order, and every side works out to 5 units. Find the length of each diagonal and name the figure.

$AC=\sqrt{(2-3{)}^2+(9-2{)}^2}=\sqrt{1+49}=\sqrt{50}=5\sqrt{2}$ and $BD=\sqrt{(-1-6{)}^2+(5-6{)}^2}=\sqrt{49+1}=5\sqrt{2}$. All four sides are equal AND the diagonals are equal, so ABCD is a square. A rhombus whose diagonals are equal is always a square, so the second option contradicts itself; 10 comes from doubling a side instead of using the distance formula.