The correct answer is option B – 3
There are 3 different elements in silver nitrate (AgNO3). It also contains 5 atoms. Silver (1 atom), Nitrogen (1) and Oxygen (3). Nitrogen and Oxygen together to form an ion called nitrate (NO3). The ionic form of silver (Ag+) combines with Nitrate (NO3) to form silver nitrate (AgNO3).

Elements and symbols present in silver nitrate
Element Symbol
Silver Ag
Nitrogen N
Oxygen O
Hope this helps.