**Concept: The question tests on applying the basics of Equation in a DS format**

**Solution:**

St (1) Reduces to 2x – y = 1

=>2x = y + 1

If y = 1 then x=1 = y (Yes )

If y = 5 then x =3 (No)

Hence **Insufficient **

St (2) Reduces to x-y = 0

x = y

(Yes)

Thus **sufficient.**

Hence **Option (b)**