Answer:
A. Son
Step-by-step explanation:
In French, we have possessive adjectives that change on whether the object is masculine or feminine. E.g. "Amelie aime son ordinateur." Even though Amelie is feminine. Or "Paul aime sa chaise."
Son = his/her for masculine objects; sa = his/her for feminine objects.
The other options:
Ses = his/her (plural obj.) (e.g. Jean a finit ses devoirs.)
Leur = their (e.g. "Ils aiment leur maison.")
Ta = your (feminine obj.) (e.g. "Tu adores ta femme.")