Answer:
a) 知 -> 吐 -> 城 -> 盛
知 CHI, shi(ru) - know
吐 TOU, ha(ku) - spew, vomit, give vent to
城 JOU, shiro - castle
盛 SEI,JOU, mo(ru), saka(n), saka(ru) - prosperous, energetic, serve food
b) 動 -> 加 -> 員 -> 贈
動 DOU , ugo(ku) - move
加 KA, kuwa(eru), kuwa(waru) - add, append, join, take part
員 IN - member
贈 ZOU, SOU, oku(ru) - give, present, bestow