Step 1: Convert each letter of each term into its position number, using A = 1 up to Z = 26.
TBLD: T = 20, B = 2, L = 12, D = 4.
VEPI: V = 22, E = 5, P = 16, I = 9.
XHTN: X = 24, H = 8, T = 20, N = 14.
Step 2: Track how each of the four letter positions changes from term to term.
1st letter: T(20) to V(22) to X(24), increasing by 2 each time.
2nd letter: B(2) to E(5) to H(8), increasing by 3 each time.
3rd letter: L(12) to P(16) to T(20), increasing by 4 each time.
4th letter: D(4) to I(9) to N(14), increasing by 5 each time.
Step 3: Apply the same increments to find the next term.
1st letter: 24 + 2 = 26, which is Z.
2nd letter: 8 + 3 = 11, which is K.
3rd letter: 20 + 4 = 24, which is X.
4th letter: 14 + 5 = 19, which is S.
Step 4: Combine the letters.
The next term is ZKXS, which matches option (3).