Question

1. $overline{ab} cong overline{ab}$

symmetric property
transitive property
definition of congruence
reflexive property

Explanation:

The reflexive property states that any geometric figure (in this case, the line - segment $\overline{AB}$) is congruent to itself. The symmetric property is about if $a\cong b$ then $b\cong a$. The transitive property is if $a\cong b$ and $b\cong c$ then $a\cong c$. The definition of congruence involves having the same size and shape in a more general sense. Here, $\overline{AB}\cong\overline{AB}$ shows the reflexive property.

Answer:

Reflexive Property