To simplify the expression \( a + b + c(d + 2) \), we start by distributing \( c \) to the terms inside the parentheses:
\[ c(d + 2) = cd + 2c \]
Now, substituting this back into the original expression gives:
\[ a + b + cd + 2c \]
Thus, the expression equivalent to \( a + b + c(d + 2) \) is:
\[ a + b + cd + 2c \]
Therefore, the correct response is:
a + b + cd + 2c