What is the cause for cloudy centers appearing in lambda plaques on an Escherichia coli confluent plate?

A) A low multiplicity of infection prevents the appearance of large numbers of lysed cells.
B) Cell debris forms a physical barrier between uninfected cells and virions.
C) Compounds in agar or nutrient medium protect bacterial cells from infection.
D) A large number of infected cells become resistant to bacteriophage infection.
E) Some infected cells become lysogens and start growing up where the infection began.