Here is a passage that tells a native american tale about a beaver. read the passage. then answer the questions.

the beaver and the pine trees, from a nez perce tale

in the old days, when trees could move on the land, only pine trees knew how to make fire. they kept this secret to themselves, guarding it as fiercely as a mother bear guards her cubs. one year a particularly frigid winter blew across the land; no one could remember it ever being so cold. ice crystals covered the animals' fur like a sparkling silver skin. their breath made billowing white clouds. they shivered like aspen1 leaves. they needed warmth to survive winter's frosty clutches. one by one, the freezing creatures went to the pine trees begging for fire; one by one, they were chased away.
one morning beaver was gnawing bark near her den when she saw one pine tree approach another and lean forward, whispering. beaver crept close and listened. there was to be a council of pine trees that very night on a hill by the frozen lake—a council with fire! after passing their message, the trees began chattering as loudly as magpies.2 they didn't hear beaver sneaking away through the undergrowth toward the lake or see her taking cover just below the bank.
beaver watched and waited patiently. as darkness stole over the land, hundreds of pine trees climbed the hill and lit a bonfire that blazed so brightly, it outshone the moon. the pine trees held their council, then sang and danced. distracted, they didn't notice when a coal came loose from the fire and began rolling downhill. beaver darted out from her hiding place, snatched the coal, and took off running.
the pine trees shouted and raced after beaver. as she zigzagged back and forth to escape, the burning coal gouged a deep path through the land. that winding furrow became a river, each bend reminding us of beaver's cleverness and courage. beaver ran so far and fast, the pine trees finally stopped, exhausted. they haven't moved since. you can still see them rooted along the river's banks, as dense as the hairs on a bear's coat.
and what, you may wonder, did beaver do with that coal? as she ran, she tossed glowing embers to the birch and willow trees. even now they hold those embers deep within them. if you're ever freezing cold, gather sticks from those generous trees, rub them together the right way, and they'll release the fire that beaver brought so everyone could be warm.

questions:

which of these events from the passage best supports the idea that beaver had a plan to get fire from the pine trees?
a beaver watched and waited patiently.
b beaver was gnawing bark near her den.
c the pine trees began whispering to each other.
d the pine trees held a council on a hill by the lake.