Four letter palindromic vowel series – UGC NET Question

Each of these terms is a four letter palindrome where the first and last letters are the same and the middle pair are also the same. From ANNA to BOOB to CPPC to DQQD, the outer letters move forward A, B, C, D while the inner letters move forward N, O, P, Q. To follow the pattern, the next outer letter must be E and the next inner letter must be R, one step after Q. This yields ERRE, which alone preserves both the palindromic form and the steady increase of the inner and outer letters, making it the correct next term.

Option A:
Option A, ESSE, uses E at the ends but changes the inner letter to S, which is not the next letter after Q in the sequence. The inner series N, O, P, Q would be broken if S were used. Because it neglects the simple one step growth of the inner letters, ESSE cannot be correct here.

Option B:
Option B is correct because ERRE places E at both ends as the next outer letter and R in the middle as the next inner letter after Q. The structure mirrors that of all previous terms and continues both sequences smoothly. This perfect match with the dual progression of outer and inner letters confirms ERRE as the right continuation.

Option C:
Option C, ERTE, breaks the rule that the middle two letters must be identical by using R and T. The series has consistently kept the second and third letters the same. Since ERTE does not retain this palindromic property, it does not follow the pattern.

Option D:
Option D, FRRF, starts with F instead of E, jumping the outer letter two steps ahead rather than one. It also interferes with the simple progression of the inner letters. Therefore FRRF is inconsistent with the rule governing the series.