Which of the following is NOT a valid deadlock prevention scheme?

Let m[0] ..m[4] be mutexes (binary semaphores) and P[0] ...P[4] be processes. Suppose each process P[i] executes the following:

wait (m[i]); wait (m(m[(i+1) mod 4]))0;
.......
release (m[i]); release (m[(i+1) mod 4]);

This could cause

The following C declarations

struct node{
  int i:
  float j;
};
struct node *s[10];

define s to be

The most appropriate matching for the following pairs

X: m=malloc(5); m= NULL;
Y: free(n); n->value = 5;
Z: char *p; *p='a';

1: using dangling
2: using uninitialized pointers
3. lost memory
is: