Try this:
Code:
#include<stdio.h>
#include<conio.h>
main()
{
char choice;
char ao;
clrscr();
gotoxy(30,3);printf("[.....MENU.....]");
gotoxy(20,6);printf("[A]");
gotoxy(25,7);printf("[45 per/kilo] *** Apple");
gotoxy(25,8);printf("[15 per/kilo] *** Orange");

gotoxy(20,11);printf("[b]");
gotoxy(25,12);printf("[12 per/kilo] *** Water Milon");
gotoxy(25,13);printf("[70 per/kilo] *** Mangustin");

gotoxy(20,16);printf("[C]");
gotoxy(25,17);printf("[200 per/kilo] *** Lemon");
gotoxy(25,18);printf("[50 per/kilo] *** Mandarin");

gotoxy(20,21);printf("[D]");
gotoxy(25,22);printf("[55 per/kilo] *** Durian");
gotoxy(25,23);printf("[30 per/kilo] *** Custard Apple");

choice=getche();
switch(choice) {
case 'a':clrscr();
	printf("i want to show this text Only when i choice A? ");
	break;
case 'b':
	printf("nothing");
	break;
}
getch();
return 0;
}
...