When armed with a Chord Wheel, even a complete music theory novice would recognize that the C7 chord is not truly 'in key,' but because it functions as the ?Secondary Dominant? (i.e. the V of V) it will fit in nicely into a composition in the key of Bb. If this is the reason you selected this answer...YOU'RE RIGHT!!
If you haven't taken years of college courses in music theory nor have you been fortunate to run across the Chord Wheel and you simply just guessed? YOU'RE WRONG!!
But don't worry. You can now achieve that level of comprehension you've always known was critical without the confusing traditional textbooks. All for less than the price of a single concert ticket!
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