The Primary Coil of an Ideal Transformer Has 100 Turns $120 \mathrm {~V}$

Multiple Choice

The primary coil of an ideal transformer has 100 turns and its secondary coil has 400 turns. If the ac voltage applied to the primary coil is $120 \mathrm {~V}$ , what voltage is present in its secondary coil?

A) $400 \mathrm {~V}$
B) $30 \mathrm {~V}$
C) $100 \mathrm {~V}$
D) $480 \mathrm {~V}$
E) $70 \mathrm {~V}$