c 从字符串数组中选择特定的字符串

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
/*
* 输入2个字符串S1和S2，要求删除字符串S1中出现的所有子串S2，
* 即结果字符串中不能包含S2。
* 提示：输入数据的设计使得不可能出现输出为空的情况。
*/
char* slectStr(char** r,char** s,int a,int b);
int main(void)
{
    char R[5][50] =
    {
        "Unreadable",
        "Barely readable, occasional words distinguishable",
        "Readable with considerable difficulty",
        "Readable with practically no difficulty",
        "Perfectly readable",
    };
    char S[9][50] =
    {
        "Faint signals, barely perceptible",
        "Very weak signals",
        "Weak signals",
        "Fair signals",
        "Fairly good signals",
        "Good signals",
        "Moderately strong signals",
        "Strong signals",
        "Extremely strong signals",
    };

    int rIndex = 1;
    int sIndex = 3;
    char* left = R[rIndex -1];
    char* right = S[sIndex-1];
    strlwr(right);
    strcat(left,", ");
    strcat(left,right);

    printf("%s",left);

    return 0;
}

/*
console log：

Unreadable, weak signals
Process returned 0 (0x0)   execution time : 0.675 s
Press any key to continue.
*/

问题：如何通过函数实现，从字符串数组中，返回特定字符串？