In gymnosperms like Pinus and Cycas, the endosaperm is

(a) triploid

(b) haploid

(c) diplod

(d) tetraploid

gymnosperm refers to a plant of a group that comprises those that have seeds unprotected by an ovary or fruit, including the conifers, cycads, and ginkgo.
so, option no b will turn out to be the correct option as their endosperm are haploid cell . 
pinus and cycas will form a good examples of gynosperm plant . 
HOPE U ARE CLEAR WITH IT 
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The option (b) is correct. in gymnosperm like pinus,cycas,cedrus trees  the endosperm is HAPLOID.

Gymnosperm are woody trees with like appearance.They bear no fruit,no flower but bear seeds.The seed are naked not covered with fruit wall.