Mariana porque no vio la escalera.
A. se caía
B. te caiste
C. se cae
O D. se cayó

Mariana se cayó  porque no vio la escalera.

The answer would be "se cayó" because that means "fell down"

For, B te caiste if someone was saying it to another person. For A se caía it doesn't make sense to put it in the sentence because it wouldn't sound good.

For C  se cea would make the sentence sound and you use it for a different sentences.

So "se cayó" is the best answer

Hope this helps

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