If f(t) = cos(at) + atsin(at), its Laplace transform is given by?

• A. ( frac{s+a}{s-a} )
• B. ( frac{a^3}{(s^2+a^2)^2} )
• C. ( frac{s(s^2+3a^2)}{(s^2+a^2)^2} )
• D. Does not exist