Phrase "twice larger than..."?

I’ve seen the following sentences.

a. His room is twice as large as mine.
b. His room is twice larger than mine.
c. His room is two times larger than mine.

I know a. is correct, but are b. and c. acceptable?

Thanks in advance!

Hi,

I’m happiest with (a).but (b) isn’t acceptable. The use of ‘two times’ isn’t wrong but ‘twice’ is more readily acceptable. I think you would use ‘two times’ if you really wanted to emphasize that it was double the size.

Alan