Simplify 6 - 4[x + 1 - (y + 3)] + 5y.

First simplify inside the brackets: x + 1 - (y + 3) = x - y - 2. Distribute -4 to get -4x + 4y + 8, then combine with the remaining terms: 6 - 4x + 4y + 8 + 5y = 14 - 4x + 9y. The result is choice C, 14 - 4x + 9y.

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