The coding pattern alternates between adding 3 and subtracting 3 from letter positions: B(+3)E, H(-3)E, O(+3)R, P(-3)M, A(+3)D, L(-3)I. Applying this to POWDER: P(-3)S, O(+3)R, W(-3)T, D(+3)G, E(-3)B, R(+3)U, which gives SRTGBU. However, reversing the alternating pattern gives: P(+3)S, O(-3)L, W(+3)Z, D(-3)A, E(+3)H, R(-3)O, which matches option B 'SLZAHO'.