Write the element stiffness matrix for a beam element.

• A. K= ( frac{2EI}{l} )
• B. K= ( frac{2EI}{l} begin{bmatrix}2 & 1 1 & 2 end{bmatrix} )
• C. K= ( frac{2E}{l} begin{bmatrix}2 1 end{bmatrix} )
• D. K= ( frac{2E}{l} begin{bmatrix}1 & 1 1 & 1 end{bmatrix} )