The Short-Time approximation is a method introduced to evaluate electroweak nuclear response for systems with A≥12, extending the reach of first-principle many-body Quantum Monte Carlo calculations. Using realistic two- and three-body nuclear interactions and consistent one- and two-body electromagnetic currents, we calculate longitudinal and transverse response densities and response functions of 12C. We compare the resulting cross sections with experimental data for electron-nucleus scattering, finding good agreement.