Choice Bhoice D is the correct answer.

1. Define: $x, x+1, x+2$. Middle is $x+1$.
2. Equation: $x + (x+1) + (x+2) = 33$
3. Simplify: $3x + 3 = 33$
4. Subtract 3: $3x = 30$
5. Divide by 3: $x = 10$
6. Middle: $x + 1 = 11$
7. Verify: $10 + 11 + 12 = 33$ ✓

Choice Bhoice C is incorrect because this is the smallest.

Choice Bhoice A is incorrect because this is the largest.

Choice Bhoice C is incorrect because calculation error.