97.Which of the following statements are correct about the String Class in C#.NET?

1.Two strings can be concatenated by using an expression of the form s3 = s1 + s2;
2.String is a primitive in C#.NET.
3.A string built using StringBuilder Class is Mutable.
4.A string built using String Class is Immutable.
5.Two strings can be concatenated by using an expression of the form s3 = s1&s2;
A.1, 2, 5
B.2, 4
C.1, 3, 4
D.3, 5
Answer: Option C