Answer:
a) 篤 -> 駐 -> 素 -> 編
篤 TOKU - serious, cordial
駐 CHUU - stop, reside
素 SO, SU - element, naked, simple
編 HEN, a(mu) - knit, crochet, compile
b) 架 -> 柱 -> 素 -> 縮
架 KA, ka(keru), ka(karu) - hang, build (a bridge)
柱 CHUU, hashira - pillar, column, pole
素 SO, SU - element, naked, simple
縮 SHUKU, chiji(maru), chiji(meru), chiji(rasu), chiji(reru) - shrink, contract, make curly