Search for grammatical errors in the underlined sections of the following sentences and select the option that best corrects them. If there is no error, choose option A.

Still, the fact that a planet exists outside our solar system encourages hope that other solar systems exist, and in them, perhaps, a planet that supports life.

that a planet exists outside our solar system encourages hope that other solar systems exist, and
that a Planet exists out side our solar system encourages hope that other solar systems exist and
could be that a planet exists outside our solar system encourages hope that other solar systems exist, and
that a planet exist outside our solar systems encourage hope that other solar systems exist, and
that a planet does exists out side our solar system encourages hope that other solar systems exist, and

The second sentence cannot be possible, for it has a capital letter in the word planet and shouldn't be capitalized as it isn't a proper noun, and also, it took off commas where there were actually corrected put.

The third sentence isn't possible either, as adding a modal verb, in this example is "could", doesn't add much meaning, just the opposite, it gets confusing and doesn't make sense, for it doesn't belong there.

The fourth one, has taken off the "s" in the verb "exist" and that was correct, because it's talking about a third person singular (it) the planet.

And finally, the last option includes an auciliary "does" and the word "outside" splited, which should't have done it, as "outside" is properly expresses and there's no need of an auxiliary in this affirmative statement.