What is the formula for the compound that occurs when Titanium (IV) and Sulfur combine ionically?

Explanation:

Titanium (IV) has a charge of +4, we know that from the Roman numeral after the element name

Sulfur has a charge of -2, we know that from its group number on the periodic table. Sulfur is in Group 16, so 16-18=-2 (there are other ways to find the charge of an element but this is easy to remember. If the element is in Group 1-3, then the charge would just be the group number.)

To balance +4, we need two -2 (ionic compounds should have zero net charge)

Therefore, we need one Titanium (IV) and two Sulfur, which becomes

the answer to your question is c