I’m assuming you mean 5g of magnesium :)
Answer is: A) The solution turns blue litmus to red.
Sulfuric acid (H₂SO₄) is a strong acid, it means that the solution of sufuric acid is more acidic (pH<7) than water (pH = 7).
Chemical dissociation of sulfuric acid in water:
H₂SO₄(aq) → 2H⁺(aq) + SO₄²⁻(aq).
When solution turns phenolphthalein pink, it means it is basic (pH>7).
Sulfuric acid has more hydrogen ions (H⁺) and less hydroxide ions (OH⁻) than water.
