A and C are grammatically correct.
Translation of A: We see a snake.
Translation of C: We see Sergio.
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B and D are missing a small word.
Correction of B: Nosotros vemos *A* Tomas.
Correction of D: Nosotros vemos *A* Jorge.
They are both missing the word "a."
The answer is the letter "B" because the gender is female
Voy a ir a la casa de mi amigo.
