Which sentence is correct?

Les chiens de filles sont gentils.
Les chiens des filles sont gentils.

The second sentence is correct.

des is a contraction of "de les."

To determine which sentence is correct, let's break it down.

1. "Les chiens de filles sont gentils."

2. "Les chiens des filles sont gentils."

Both sentences are talking about dogs (les chiens) that belong to girls (de filles / des filles). The difference lies in the use of the preposition "de" and the contraction "des".

In French, the preposition "de" can indicate possession. However, when it is used before a plural noun, it can be contracted into "des".

Now, let's analyze each sentence:

1. "Les chiens de filles sont gentils."

Here, the preposition "de" is used before the plural noun "filles." However, since "filles" is plural, the correct contraction should be "des" instead of "de." Therefore, this sentence is incorrect.

2. "Les chiens des filles sont gentils."

In this sentence, the contraction "des" is used correctly before the plural noun "filles". Therefore, this sentence is correct.

So, the correct sentence is:

"Les chiens des filles sont gentils."