A delta-star transformer has a phase to phase voltage transformation ratio of a : 1 [delta phase : star phase]. The line to line voltage ratio of star-delta is given by

A

$$\frac{a}{1}$$

B

$$\frac{\sqrt{3}}{\sqrt{a}}$$

C

$$a\frac{\sqrt{3}}{1}$$

D

$$\frac{\sqrt{3}}{a}$$