Field induced trapping on a line segment of a diffusion-driven system is studied with an aim to gain an insight into the occurrence of coherent stochastic resonance, which is thoroughly explored as synchronized mean-free passages to the traps. Synchronization (coherence) between the external bias, the noise in the system and the temporal trapping events is found to attain an optimum value by increasing the forcing frequency towards the relevant resonant frequency, revealing a minimum in the nonmonotonic mean-free-passage time (MFPT) to trapping. The MFPT at a given forcing frequency, is also nonmonotonic when considered as a function of the diffusion coefficient of the medium, and reveals a maximum exhibiting the least synchronization effect (incoherent trapping).