Answer is (c) fruits.
Pine trees reproduce by using the pine cones that appear like a hard mass hanging on the branches on the pine tree. The pine cones open up after maturing to release the pine seeds into the air. Since pine cone use this mode of reproduction, they lack the need to have flowers. In fruiting trees, the purpose of the fruit is to protect the seeds and help in the dispersal of seeds through carriers that consume them. Pine trees do not need carriers, they depend on the wind for carrying its seeds.
