Table 203
the Following Data Were Obtained from a Broth Dilution

Table 20.3
The following data were obtained from a broth dilution test:

$\begin{array}{ll}\text { Concentration of Antibiotic } X&\text { Growth }\\\hline2.0 \mu \mathrm{g} / \mathrm{ml} & - \\1.0 \mu \mathrm{g} / \mathrm{ml} & - \\0.5 \mu \mathrm{g} / \mathrm{ml} & - \\0.25 \mu \mathrm{g} / \mathrm{ml} & + \\0.125 \mu \mathrm{g} / \mathrm{ml} & + \\0 & +\end{array}$
Bacteria from the 0.25 µg/ml tube were transferred to new growth media containing antibiotic X with the following results:

$\begin{array}{ll} \underline{\text { Concentration of Antibiotic }} X& \underline{\text { Growth} }\\2.0 \mu \mathrm{g} / \mathrm{ml} \\1.0 \mu \mathrm{g} / \mathrm{ml} & - \\0.5 \mu \mathrm{g} / \mathrm{ml} & + \\0.25 \mu \mathrm{g} / \mathrm{ml} & + \\\end{array}$
-The data in Table 20.3 show that these bacteria

A) Developed resistance to antibiotics.
B) Can be subcultured.
C) Were killed by 0.5 µg/ml of antibiotic X.
D) Were killed by 0.125 µg/ml of antibiotic X.
E) Were resistant to 1.0 µg/ml at the start of the experiment.