How Can Hybridoma Cells Be Kept Alive for Extended Periods

How can hybridoma cells be kept alive for extended periods of time? (Check as many as apply.)

A) They can't. Once removed from the host animal the cells die quickly.
B) Growing them at refrigerator temperature.
C) Placing them into a susceptible host where they will form a tumor.
D) Using the appropriate cell culture techniques.
E) Growing them in a field of ionizing radiation.