Four discs, each soaked in a different antibiotic, were placed on the surface of a culture plate that had been innoculated with E. coli bacteria. The diagram below shows the culture plated
after it had been incubated for 48 hours.

Key:
Shaded area
represents E. coll
Clear area represents
absence of E. coli
Antibiotic disc
P= penicillin
E=erythromycin
8 = streptomycin
C=chloramphenicol

Whích antibiotic was most effective in inhibiting the growth of E. coli?
1.penicillin
2.erythromycin
3.streptomycin
4.chloramphenicol