Electroexcitation of the dominantly T=l particle-hole states of C are studied in the framework of the harmonic oscillator shell model. Configuration mixing is allowed and the Hamiltonian is diagonlized in the-presence of the modified surfacedelta interaction (MSDI). All possible T=l single-particle-hole states of all allowed angular moment are considered in a basis including single-particle states up to the lf-2p shell. Resulting mixed states lying close in energy are grouped together into complexes whose inelastic electron scattering form factors are then compared with recent experimental data. Correlation in the ground state wave functions by mixing more than one configuration is considered and shows a major contribution that leads to enhance the calculations of the form factors.