Answer:
[tex]\textsf{A)}\quad \overline{MP}[/tex]
Step-by-step explanation:
A common side of two triangles refers to a side that is shared by both triangles.
In triangle NPM, the sides are NP, PM and NM.
In triangle OMP, the sides are OM, MP and OP.
In this case, both triangles have a side labeled MP (note that the order of the letters doesn't matter), making this side common to both triangles.
