Answer: Option (A) is the correct answer.
Step-by-step explanation:
When two atoms share electrons then it results in the formation of covalent bond. Whereas when there is transfer of electrons between two atoms then it forms an ionic bond.
Sodium is a metal so it has excess of electrons whereas iodine is a non-metal so it is electron deficient.
So, sodium will give its extra electron to iodine thus due to transfer of electron it results in the formation of ionic bond.