Answer:
a) 章 -> 古 -> 吐 -> 堀
章 SHOU - chapter, badge, mark
古 KO, furu(i) - old
吐 TOU, ha(ku) - spew, vomit, give vent to
堀 hori - moat, canal, ditch
b) 基 -> 埋 -> 野 -> 預
基 KI, moto, motoi - basis, foundation
埋 MAI, u(maru), u(meru), u(moreru) - bury, be buried, filled up
野 YA, no - field, plain
預 YO, azu(keru), azu(karu) - entrust