Final answer:
Contact inhibition is the biggest conflict for cell culture, as it prevents cells from dividing at high densities. Continuous cell lines can overcome contact inhibition and continue to grow.
Step-by-step explanation:
The biggest conflict for cell culture is contact inhibition. Contact inhibition occurs when cells come in contact with each other and stop dividing, preventing the density of the cells from becoming too high. This limits the growth of primary cell cultures. Continuous cell lines, derived from transformed cells or tumors, can overcome contact inhibition and continue to grow even at high densities.