Pines,including the Whitebark Pine,are Pioneer-Type Trees,meaning the Young Seedlings and Trees

Pines,including the whitebark pine,are pioneer-type trees,meaning the young seedlings and trees need to grow in open areas with sunlight.Which of these would be most helpful in spreading the seeds of the trees?

A) bears,which eat and digest the seeds
B) squirrels,which bury the seeds in the shade of the pines
C) rodents,which cache the seeds in their deep underground burrows
D) Clark's nutcracker,which caches the seeds on sunny hillsides