To simplify the expression [tex]\( 12 \sqrt{6} + 4 \sqrt{6} \)[/tex], we follow these steps:
1. Identify like terms: Both terms have the square root of 6, so they are like terms.
2. Combine the coefficients: We add the coefficients of the like terms together.
Thus, we start with:
[tex]\[ 12 \sqrt{6} + 4 \sqrt{6}. \][/tex]
We combine the coefficients 12 and 4:
[tex]\[ 12 + 4 = 16. \][/tex]
So the expression simplifies to:
[tex]\[ 16 \sqrt{6}. \][/tex]
Therefore, the correct answer is:
[tex]\[ \boxed{16 \sqrt{6}} \][/tex]
The answer is D.
