Step 1: Check the expression \(3x+2y\) at each vertex.
The vertices of the triangle are
\[
(1,3),\quad (5,0),\quad (-1,2).
\]
For \((1,3)\),
\[
3x+2y=3(1)+2(3)=3+6=9.
\]
For \((5,0)\),
\[
3x+2y=3(5)+2(0)=15.
\]
For \((-1,2)\),
\[
3x+2y=3(-1)+2(2)=-3+4=1.
\]
Step 2: Observe the sign.
At all three vertices,
\[
3x+2y>0.
\]
Since the triangle is the convex region formed by these vertices, every point inside the triangle also lies on the same side of the line
\[
3x+2y=0.
\]
Therefore, all interior points satisfy
\[
3x+2y>0.
\]
Step 3: Check why other options are not necessary.
Option (1) says
\[
3x+2y\leq 0,
\]
which is false because all vertices give positive values.
Option (3) says
\[
2x-3y-12>0.
\]
At \((5,0)\),
\[
2(5)-3(0)-12=-2<0,
\]
so this is not necessarily true.
Option (4) says
\[
2x+y-13>0.
\]
At \((5,0)\),
\[
2(5)+0-13=-3<0,
\]
so this is also not necessarily true.
Step 4: Final conclusion.
Hence, all points inside the triangle must satisfy
\[
\boxed{3x+2y>0}
\]