When is your birthday?

My birthday is April 19th.
My birthday is on April 19th.
It is April 19th.
It is on April 19th.

-----------
There are 4 answers above.
Which answers are right?
Are all correct answers?
Which ones are commonly used?

1 answer

The only one of those that is really awkward is "It is April 19th." The subject of the "it" is not clear.