Can someone please check-over these answers I got to my Spanish homework?

Question

Subject: Double Object Pronouns

Instructions: Complete the translation of the sentences in bold by writing the direct and indirect object pronouns on the lines. Clues are in parenthesis for the object pronouns. 

Example:

Diana rents the car for them.

 Diana se lo alquila. (el auto)

Questions:

1. Jorge gives the book to me. Jorge gives it to me. (el libro)  

Answer: Jorge me lo da.

2. Luisa serves the salad to us. Luisa serves it to us. (la ensalada)

Answer: Luisa nos lo sirve.

3. I show the photos to Elena. I show them to her. (las fotos)

Answer: Yo se los muestro.

Answer 1

Number 1 is correct, but number 2 and 3 are wrong.

Number 2 is:

Luisa nos la sirve. (because ensalada es female/singular)

Number 3 is:

Yo se las muestro. (because fotos is female/plural)