The Term Primary Cell Line Refers to

The term primary cell line refers to

A) those lines that cannot be subcultured more than once or twice to avoid decreased receptivity to viral infection.
B) those lines that remain virus-sensitive through not more than 10 subcultures.
C) those lines that remain virus-sensitive through 20 to 50 subcultures.
D) those lines that can be subcultured and remain sensitive to virus infections indefinitely.