French grammar:(téléphoner: a verb followed by the preposition 'à')

Question

Could you help me out with this short French grammar question...

Q-) Choisissez la bonne réponse:

"Nous téléphonons à ami de Nathalie."

Ou

"Nous téléphonons à l'ami de Nathalie."

From the above two sentences, which one is correct...also please provide me with the appropriate reason for the correct answer.

Accepted Answer

Hi Babit, 
Nous téléphonons à l'ami de Nathalie 
is correct and literally it says-
we are ringing the friend of Nathalie = we are ringing Nathalie's friend 
using the construction the .... of 
as in -
La plume de ma tante est sur le bureau de mon oncle = My aunt's pen is on my uncle's desk
the Kwiziq lesson you are looking for is the following one -
https://french.kwiziq.com/revision/grammar/how-to-express-possession-with-de
Hope this helps!

Answer

Nous téléphonons à l'ami de Nathalie. -- We're calling Natalie's friend. The article is needed.