¿De quién?

Question

De quién was an option for this question:

Mi perro, ________ me acuerdo a menudo, ha muerto recientemente.

However when I selected it I was marked wrong.

However according to this page

Using preposition a and de + el que, la que, los que, las que = to/of/from/about which/who (relative pronouns)

Should I have been marked right because quién doesn't necessarily need to pair with a lo/la?

Answer

Hola Chris
With pets, in Spanish we don't normally use the relative "quien" - there's this note in the lesson:
Note that, while in English the relative pronoun "who" is often used to refer to pets, in Spain it is not generally used.
"Mi gato, del que tengo muchas fotos, es adorable."
"My cat, who I have lots of pictures of, is adorable"
 
This is why that option wasn't marked as correct.
I hope it clarifies it.
Saludos