The base data type of a pointer variable, by which the memory is allocated to it, depends on the type of the variable the pointer is pointing to. In C and C++, a pointer is declared with a specific data type that indicates the type of data stored at the memory location it points to. This data type determines the amount of memory allocated and how pointer arithmetic is performed. For example, if you declare a pointer as int *ptr;, the base data type is int. When you allocate memory for this pointer dynamically using malloc or new, the size of the allocated memory is based on the size of int:

c

int *ptr = malloc(20 * sizeof(int));

Here, memory for 20 integers is allocated because the pointer's base type is int. The pointer itself stores the address of the first integer in the allocated block

. Thus, the base data type of a pointer variable is the data type of the variable it points to, which guides how much memory is allocated and how the pointer is used. This is summarized as:

• The pointer's base data type is the type of the data it points to (e.g., int, float, double).
• Memory allocation size is computed using sizeof on the base data type.
• Pointer arithmetic is done in units of the base data type size.

In multiple-choice terms, the correct answer is: D. Depends upon the type of the variable to which it is pointing

. This means the pointer's base data type is not fixed but depends on what it points to, which is essential for correct memory allocation and access.