How to write data on multiple lines BUT within the same cell of csv?

Question

I want to create one csv file using C#.

I have some data which I want to write on multiple lines BUT within the same cell.

For example If I have following t

Answer 1

string input = "...";

var r = input.Split(new[] { '.' }, StringSplitOptions.RemoveEmptyEntries) // split by dot (have you any better approaches?)
             .Select(s => String.Format("\"{0}.\"", s.Trim())); // escape each with quotes

input = String.Join(Environment.NewLine, r); // break by line break