Question

identify the conclusion in the following statement: if the measures of two angles add to 180°, then they are supplementary by the definition of supplementary angles.
. . . then they are supplementary . . .
if the measures of two angles add to 180° . . .
. . . by the definition of supplementary angles.
none of the above.

Explanation:

In an "if - then" statement, the part following "then" is the conclusion. Here, the statement is "If the measures of two angles add to 180°, then they are supplementary by the definition of supplementary angles". So the conclusion is the part after "then".

Answer:

A. ... then they are supplementary ...