3. The vertices of a quadrilateral lie on the sides of a square with side length 1. If the sum of the squares of the four sides is $t$, then the range of values for $t$ is ( ).
(A) $[1,2]$
(B) $[2,4]$
(C) $[1,3]$
(D) $[3,6]$
3. B.

When the vertices of the quadrilateral coincide with the vertices of the square, we know $t=4$, thus eliminating options (A) and (C); when taking the midpoints of each side, we get $t=2$, thus eliminating option (D).