use the following diagram and information to answer the question.
given: abcd is a parallelogram. △abc≅△bcd
julie wants to prove that abcd is a square. she uses properties of congruent triangles and parallelograms to prove that ∠a≅∠b≅∠c≅∠d. she must also show that ab≅bc≅cd≅da to prove abcd is a square.

what else must julie do to prove abcd is a square?
a) julie can use properties of congruent triangles to show that ab¯≅cd and ad≅bc. then she can use the definition of parallelogram to show ab≅bc.
b) julie can use properties of congruent triangles to show that ab≅bc and bc≅cd. then she can show bc≅ad because opposite sides of a parallelogram are congruent.
c) julie can use the definition of a parallelogram to show that ab≅bc and bc≅cd. then she can use the definition of congruent triangles to show bc≅ad.
d)julie can use properties of congruent triangles to show that ac≅bd. then she can use the definition of parallelogram to show bc≅ad.