Step 1: Define each event clearly
We list all possible sums for each event:
Event A (even sum):
\[
\{2,4,6,8,10,12\}
\]
Event B (multiple of 3):
\[
\{3,6,9,12\}
\]
Event C (sum less than 4):
\[
\{2,3\}
\]
Event D (sum greater than 11):
\[
\{12\}
\]
Step 2: Check intersections
We check each option:
(A and B):
\[
\{2,4,6,8,10,12\} \cap \{3,6,9,12\} = \{6,12\} \neq \emptyset
\]
(B and D):
\[
\{3,6,9,12\} \cap \{12\} = \{12\} \neq \emptyset
\]
(A and C):
\[
\{2,4,6,8,10,12\} \cap \{2,3\} = \{2\} \neq \emptyset
\]
(C and D):
\[
\{2,3\} \cap \{12\} = \emptyset
\]
Thus, only C and D are mutually exclusive.