17. Consider the following "C" code segment. At least how many test cases are needed for achieving decision coverage for the given C code? int main (){ inta,b=0; scanf("%d",&a); if( a 100) b=b+10; if( a == 20 ) b=b+20; else b++; if( a == 30 ) b=b+30; else b=b+40; } } oo 8 3 4 5