The formula for the surface area of a triangular prism can be expressed as:
\[ S.A. = bh + (S_1 + S_2 + S_3) \cdot l \]
Where:
- \( b \) is the base of the triangle,
- \( h \) is the height of the triangular base,
- \( S_1, S_2, \) and \( S_3 \) are the lengths of the sides of the triangular base, and
- \( l \) is the length (or height) of the prism.
So, the correct response from the options you provided is:
S. A. = bh + (S1 + S2 + S3)⋅l.