Please help In a quadrilateral ABCD, the diagonals intersect at point T. Heather has used the Alternate Interior Angles Theorem to show that angle ABD is congruent to angle CDB and that angle BAC is congruent to DCA.

Which of the following can Heather use prove that segment DT is equal to segment TB?

AB ≅ DC
AC ≅ DB
DA ≅ BC
AC ≅ AC