If you have a violin song in Concert C major, what would be the Bb Clarinet key

Question:

If you have a violin song in Concert C major, what would be the Bb Clarinet key for the same song? QUICKLY!!!!

I'm writing out a trio for the song "It is Well With My Soul" with the song being in Concert C major. I thought Bb Clarinet would go to D major, but maybe it is Bb? I'm very very very confused and need the answer now. Please help.

Best Answer - Chosen by Asker:

You were initially correct! Because the Bb Clarinet sounds a whole step lower than it is written, you need to compensate for that by writing it up one step from non-transposing instruments. Therefore, if you write its part in D Major (Two sharps - F# and C#) the notes it plays will sound a whole step lower - in C Major.

Also, just a side note: I'm a music major in college and have studied music since I was in 3rd grade, don't get discouraged by transposition, it throws everyone off, even professionals!! ;)