Complex sentence: At the most basic level, the PSI answers the question if a particular supplier, the "pivotal supplier", is needed to supply the demand: would it be possible to supply the electricity demand also without this supplier or is he mandatory ?
Split into simpler sentences: At the most basic level the PSI answers the question if a particular supplier, the "pivotal supplier", is needed to supply the demand. Would it be possible to supply the electricity demand also without this supplier or is he mandatory?