Concept:Simplify the integrand using trigonometric identities, then substitute u=tanx.Explanation:Rewrite sinxcosx as tanxcos2x:sinxcosxtanx=tanxcos2xtanx=tanxsec2x.So the integral becomes:I=∫tanxsec2xdx.Let u=tanx, then du=sec2xdx.Substitute and integrate:I=∫udu=∫u−1/2du=2u+c.Replace u with tanx:∫sinxcosxtanxdx=2tanx+c.Answer:B. 2tanx+c, where c is a constant of integration.