- Observing the pattern in the first pair \( \text{BEGK} : \text{ADFJ} \), we notice that each letter in the second term is obtained by shifting the corresponding letter in the first term backward by 1 position:
\[
B \rightarrow A, \quad E \rightarrow D, \quad G \rightarrow F, \quad K \rightarrow J.
\]
- Applying the same pattern to \( \text{PSVY} \):
\[
P \rightarrow O, \quad S \rightarrow R, \quad V \rightarrow U, \quad Y \rightarrow X.
\]
Thus, the missing term is \( \mathbf{ORUX} \).