belong to the class
a)	Gnetopsida	b)	Cycadopsida	c)	Coniferopsida	d)	Sphenopsida

(c)

 belongs to Coniferopsida. The mature plant is large tree growing upto 30-70 m in height and differentiated into root, stem and leaves. Branches are arranged in acropetal order thus, giving the pyramid or conical shaped appearance to the tree.