Consider a vector field $$\overrightarrow {\text{A}} \left( {\overrightarrow {\text{r}} } \right).$$ The closed loop line integral $$\oint {\overrightarrow {\text{A}} \cdot \overrightarrow {{\text{d}}l} } $$ can be expressed as A. $$\mathop{{\int\!\!\!\!\!\int}\mkern-21mu \bigcirc} {\left( {\nabla \times \overrightarrow {\text{A}} } \right) \cdot \overrightarrow {{\text{ds}}} } $$ over the closed surface bounded by the loop B. $$\mathop{{\int\!\!\!\!\!\int\!\!\!\!\!\int}\mkern-31.2mu \bigodot} {\left( {\nabla \cdot \overrightarrow {\text{A}} } \right){\text{dv}}} $$ over the closed volume bounded by the top C. $$\iiint {\left( {\nabla \cdot \overrightarrow {\text{A}} } \right){\text{dv}}}$$ over the open volume bounded by the loop D. $$\iint {\left( {\nabla \times \overrightarrow {\text{A}} } \right) \cdot \overrightarrow {{\text{ds}}} }$$ over the open surface bounded by the loop

$$mathop{{int!!!!!int}mkern-21mu igcirc} {left( { abla imes overrightarrow { ext{A}} } ight) cdot overrightarrow {{ ext{ds}}} } $$ over the closed surface bounded by the loop
$$mathop{{int!!!!!int!!!!!int}mkern-31.2mu igodot} {left( { abla cdot overrightarrow { ext{A}} } ight){ ext{dv}}} $$ over the closed volume bounded by the top
$$iiint {left( { abla cdot overrightarrow { ext{A}} } ight){ ext{dv}}}$$ over the open volume bounded by the loop
$$iint {left( { abla imes overrightarrow { ext{A}} } ight) cdot overrightarrow {{ ext{ds}}} }$$ over the open surface bounded by the loop

The correct answer is:

$$\oint {\overrightarrow {\text{A}} \cdot \overrightarrow {{\text{d}}l} } = \mathop{{\int!!!!!\int}\mkern-21mu \bigcirc} {\left( {\nabla \times \overrightarrow {\text{A}} } \right) \cdot \overrightarrow {{\text{ds}}} } $$

This is known as Stokes’ theorem. It states that the line integral of a vector field around a closed loop is equal to the surface integral of the curl of the vector field over any surface bounded by the loop.

The curl of a vector field is a measure of how much the vector field rotates around a point. It is defined as the cross product of the gradient and the vector field.

The surface integral of a vector field over a surface is the sum of the dot products of the vector field and the area element over the surface.

In this case, the vector field is $\overrightarrow {\text{A}} \left( {\overrightarrow {\text{r}} } \right)$ and the surface is the closed surface bounded by the loop. The curl of the vector field is $\nabla \times \overrightarrow {\text{A}} $.

The line integral of $\overrightarrow {\text{A}} \cdot \overrightarrow {{\text{d}}l} $ around the loop is equal to the surface integral of $\left( {\nabla \times \overrightarrow {\text{A}} } \right) \cdot \overrightarrow {{\text{ds}}} $ over the closed surface bounded by the loop.

The other options are incorrect because they do not take into account the closed surface bounded by the loop.