C#：哪个使用更多的内存开销？包含单词序列的字符串或字符？

例如

//.Net Framework allocates memory space for "word" only once,all the three variables refer to this chunk of memory
String s1,s2,s3;
s1 = "word";
s2 = "word";
s3 = "word";

//.Net Framework allocates memory for each array
char[] c1 = new char[] { 'w','o','r','d'};
char[] c2 = new char[] { 'w','d'};
char[] c3 = new char[] { 'w','d'};