Answer:
a) 粒 -> 音 -> 冒 -> 眺
粒 RYUU, tsubu - a grain
音 ON, IN, oto, ne - sound
冒 BOU , oka(su) - risk, brave, deft, dare, desecrate
眺 CHOU, naga(meru) - look at, watch, gaze
b) 粒 -> 辛 -> 古 -> 味
粒 RYUU, tsubu - a grain
辛 SHIN, kara(i) - hot, spicy, trying
古 KO, furu(i) - old
味 MI, aji , aji(wau) - taste