A voltage transformer with 220V/24V If the input alimentation tension is 220 v DC then what should be the output value ?

But here the question is a little bit tricky ! The input is220 V DC (Direct Current) that means the tension is constant not varying sinusoidal, then the transformer can'nt function and the Output voltage is zero. 

The normal working conditions of a voltage transformer is under Alternative Current (AC) 

If the input is220V AC then the ouput should be24V AC.

I agree with Labib.

Transformer is an AC equipment only.

A.24 Volts

I will choose also choice (A)24 Volts

If you have an in put  of220 V and an output  24 V than the answer should be

A output24 V

This would be a logical conclusion, since I am not an Electrical or Network Engineer 

I would appreciate if you would correct me if I am not correct 

consider this answer.

When an input voltage of220V  DC is applied, at the instant of application, you will get an output in secondary, which is around24V. After the instant of application, the output will be zero, since there is no change in voltage level.

that would be24V also DC

A