Given coefficient of variation $1=50$
Coefficient of variation $2=60$
Arithmetic mean $1=30$
Arithmetic mean $2= 25$
$CV1= \large\frac{\sigma_1}{\bar {x} _1} $$\times 100$
$=> 50 =\large\frac{\sigma 1}{30} $$ \times 100$
$\sigma_1= \large\frac{50 \times 30}{100}$
$\qquad= 15$
$CV2= \large\frac{\sigma_2}{\bar {x} _2} $$\times 100$
$60= \large\frac{\sigma_2}{25}$$ \times 2$
$\sigma _2 =\large\frac{60 \times 25}{100}$
$\qquad= \large\frac{150}{10}$$=15$
The difference b/w $\sigma_1$ and $\sigma_2$ is zero.
Hence A is the correct answer.