JEE Math Practice Question

Let R be the real line. Consider the following subsets of the plane $$R \times R$$ : $$S = \left\{ {(x,y):y = x + 1\,\,and\,\,0 < x < 2} \right\}$$ $$T = \left\{ {(x,y): x - y\,\,\,is\,\,an\,\,{\mathop{\rm int}} eger\,} \right\}$$, Which one of the following is true ?

1. A.Neither S nor T is an equivalence relation on R
2. B.Both S and T are equivalence relation on R
3. C.S is an equivalence relation on R but T is not
4. D.T is an equivalence relation on R but S is not