Question

suppose △def≅△mno. which congruency statement is true?
○ ef≅mn
○ ef≅mo
○ de≅mn
○ df≅no

Explanation:

Step1: Recall congruent - triangle property

When $\triangle DEF\cong\triangle MNO$, corresponding sides are congruent. The order of the vertices in the congruence statement matters. The first - named vertices ($D$ and $M$), the second - named vertices ($E$ and $N$), and the third - named vertices ($F$ and $O$) are corresponding.

Step2: Identify corresponding sides

Side $\overline{DE}$ corresponds to side $\overline{MN}$, side $\overline{EF}$ corresponds to side $\overline{NO}$, and side $\overline{DF}$ corresponds to side $\overline{MO}$.

Answer:

$\overline{DE}\cong\overline{MN}$