Driven by instinct, the salmon rushed upstream, the salmon neither knew nor cared about the hungry bears that awaited them. Which revision corrects the sentence?

a.
Driven by instinct, the salmon rushed upstream and neither knew nor cared about the hungry bears that awaited them.

b.
Driven by instinct, the salmon rushed upstream, they neither knew nor cared about the hungry bears that awaited them.

c.
Driven by instinct, the salmon rushed upstream. Neither knew nor cared about the hungry bears that awaited them.

d.
Driven by instinct, the salmon rushed upstream; They neither knew nor cared about the hungry bears that awaited them.

Stone, two or three feet thick, the door of wood and iron, a foot thick, and the iron grating which strained the light, i could not being struck with the foolishness of that institution which treated me as if i were mere flesh and blood and bones, to be locked up. i wondered that it should have concluded at length that this was the best use it could put me to, and had never thought to avail itself of my services in some way. i saw that, if there was a wall of stone between me and my townsmen, there was a still more difficult one to climb or break through before they could get to be as free as i was. i did not for a moment feel confined, and the walls seemed a great waste of stone and mortar. i felt as if i alone of all my townsmen had paid my tax. — “civil disobedience,” henry david thoreau based on this passage, how did thoreau feel about his confinement?

Which counter claim is most effective against this claim? rob's essay includes

The room was gaudy with its leather couch and purple walls