chemistry- acids and bases?

Question

Arrange the acids
I) phosphorous acid (H3PO3),
pKa1 = 2.00;
II) hydrogen selenate ion (HSeO¡
4 ), pKa = 1.92;
III) selenous acid (H2SeO3), pKa = 2.46;
IV) phosphoric acid (H3PO4), pKa = 2.12;
in increasing order of strengths.
1. Cannot be determined
2. IV, III, I, II
3. III, I, IV, II
4. IV, I, III, II
5. None of these
6. II, I, IV, III
7. III, IV, I, II
8. II, I, III, IV
9. II, IV, I, III
10. II, III, I, IV

Answer 1

The strongest acid has the lowest pKa.