The statement:
int *ptr;
has the same meaning as
a.
int ptr;
b.
*int ptr;
c.
int ptr*;
d.
int* ptr;

D. int* ptr;

Explanation:

int *ptr; it is pointer used to hold address of another integer variable.In the options provided we have int ptr that is an integer variable of name ptr.

*int ptr; is wrong this will give error because first we have to write the data type.

int ptr*; is an integer varaible with name ptr*.

int* ptr; is a pointer which can hold the address of another integer varaible.

answer; insolated i/o uses separate memory space,and on the other hand memory mapped i/o uses memory from the main