Question

state the postulate that verifies $overleftrightarrow{ab}$ is in plane $q$ when points $a$ and $b$ are in $q$.
$\bigcirc$ postulate 4: if two points lie in a plane, the line containing them lies in that plane.
$\bigcirc$ postulate 1a: a plane contains at least three points not all on one line.
$\bigcirc$ postulate 5: if two planes intersect, then their intersection is a line.
$\bigcirc$ postulate 1b: space contains at least four points not all on one plane.
$\bigcirc$ postulate 2: through any two different points, exactly one line exists.
$\bigcirc$ postulate 3: through any three points that are not one line, exactly one plane exists.
$\bigcirc$ postulate 1: a line contains at least two points.

Explanation:

The problem is about verifying that line \(\overleftrightarrow{AB}\) is in plane \(Q\) when points \(A\) and \(B\) are in \(Q\). Postulate 4 states that if two points (here \(A\) and \(B\)) lie in a plane (here \(Q\)), the line containing them (here \(\overleftrightarrow{AB}\)) lies in that plane, which directly matches the situation.

Answer:

Postulate 4: If two points lie in a plane, the line containing them lies in that plane.