The term 'polyadelphous' is related to
Corolla
Calyx
Gynoecium
Androecium
Adelphous is a condition when stamens are fused by their filaments only. Fusion of filaments producing many groups is called Polyadelphous.
Find the odd-man-out :
(a) node, internode, bud, root hair
(b) calyx, corolla, gynoecium, leaf apex