Question

Je telephone a mes grand-parents convert into
pronom personnel

Answer 1

Answer:

je telephone a eux

Explanation:

Answer 2

Answer:

Je leur telephone.

Explanation:

Since à + quelqu'un (à + someone/persone) is a case of COI (complement-objet-indirect) and since mes grands parents is in plural, therefore, the aforementioned would be your answer :)