<prompt> Hep-2 cells are type of -Primary cell culturesDiploid cell strainContinuous cell linesExplant culture  <response>: Continuous cell lines These are cells of a singke type usually derived from cancer cells that are capable of continuous serial cultivation indefinitely. Standard cell lines derived from human cancers such as HeLa HeP2 ank KB cell lines have been used. REF:ANANTHANARAYAN AND PANIKERS TEXTBOOK OF MICROBIOLOGY 9TH EDITION PAGE NO:435 