To determine the dimensions of stress, we need to understand what stress is.$\\$Stress is defined as force per unit area. Mathematically, it is expressed as:$\\$Stress$= \frac{Force}{Area} \\$Let's find the dimensions of force and area separately:$\\$• Force is defined as mass times acceleration. The dimensional formula for force is:$\\$Force$=$mass$\times$acceleration$\\$The dimension of mass is $[M],$ and the dimension of acceleration is $[L T^{-2}]. \\$Therefore, the dimension of force is $[M L T^{-2}]. \\$• Area is a measure of a two-dimensional surface, and its dimension is $[L^2]. \\$Now, substitute these dimensions into the formula for stress:$\\$Stress$= \frac{Force}{Area} = \frac{[M L T^{-2}]}{[L^2]} \\$Simplify the expression:$\\$Stress$= [M L^{-1} T^{-2}] \\$Therefore, the dimensions of stress are $[M L^{-1} T^{-2}]. \\$This corresponds to Option 3.