Final answer:
The correct way to declare two pointers at once is to use int *ptr1; int *ptr2.
Step-by-step explanation:
The correct way to declare two pointers at once is option B: int *ptr1; int *ptr2. In this option, each pointer is declared separately with its own asterisk (*) symbol. This ensures that both ptr1 and ptr2 are declared as integer pointers. In option A, only ptr1 is declared as a pointer, while ptr2 is declared as a regular int. Option C declares ptr1 as a regular int and ptr2 as an integer pointer, which is the opposite of what is desired. Option D declares ptr1 as a regular int and ptr2 as a reference to an int, which is different from a pointer.