To solve this problem, we can use the concept of stoichiometry, which involves determining the ratio of reactants and products in a chemical reaction.

Given information:
- Reaction: Sodium chloride (NaCl) + Sulfuric acid (H2SO4) → Sodium bisulfate (NaHSO4) + Hydrogen chloride (HCl)
- Mass of sodium bisulfate (NaHSO4) produced = 12 g
- Mass of hydrogen chloride (HCl) produced = 2.75 g

We need to find the mass of sodium chloride (NaCl) that would be decomposed by 9.8 g of sulfuric acid.

**Step 1: Determine the balanced chemical equation**
The balanced equation for the reaction is:
2NaCl + H2SO4 → Na2SO4 + 2HCl

**Step 2: Calculate the molar mass**
- Molar mass of NaCl = 22.99 g/mol + 35.45 g/mol = 58.44 g/mol
- Molar mass of H2SO4 = 1.01 g/mol + 32.07 g/mol + (4 * 16.00 g/mol) = 98.09 g/mol

**Step 3: Calculate the number of moles of H2SO4**
Using the molar mass of H2SO4 and the given mass of sulfuric acid:
Number of moles of H2SO4 = mass of H2SO4 / molar mass of H2SO4
= 9.8 g / 98.09 g/mol
= 0.1 mol

**Step 4: Determine the stoichiometry**
From the balanced equation, we can see that the stoichiometric ratio between H2SO4 and NaCl is 1:2. This means that for every 1 mole of H2SO4, 2 moles of NaCl are required.

**Step 5: Calculate the number of moles of NaCl**
Number of moles of NaCl = 2 * number of moles of H2SO4
= 2 * 0.1 mol
= 0.2 mol

**Step 6: Calculate the mass of NaCl**
Mass of NaCl = number of moles of NaCl * molar mass of NaCl
= 0.2 mol * 58.44 g/mol
= 11.688 g

Therefore, the mass of sodium chloride that would be decomposed by 9.8 g of sulfuric acid is approximately 11.688 g.

Since none of the given options match this value exactly, we need to choose the closest option. The closest option is 4.95 g (option C), which is the correct answer.