Concept:
This is a coding-decoding problem based on rearrangement of letters in a pattern.
Step 1: Understand the pattern from given example.
\[
\text{CONDEMN} \rightarrow \text{CNODMEN}
\]
Break into pairs:
\[
CO\ ND\ EM\ N
\]
Rearranged as:
\[
CN\ OD\ ME\ N
\]
So pattern:
\[
(1,2) \rightarrow (1,3), (2,4), (3,5), \ldots
\]
Actually observed pattern:
• 1st stays
• 3rd comes next
• 2nd shifts after
• then normal continuation
Step 2: Apply same to TEACHER.
\[
T\ E\ A\ C\ H\ E\ R
\]
Rearrange:
\[
T,\ A,\ E,\ C,\ H,\ E,\ R
\]
So pattern becomes:
\[
TAECHER
\]
Now match with given format:
\[
CT\_\_E\_\_
\]
Thus fill letters accordingly:
\[
D,\ C,\ A,\ B
\]
Step 3: Final answer.
\[
\boxed{(3)\ D,\ C,\ A,\ B}
\]