The correct answer is B.
The expression $c = i++$ is a pre-increment expression. This means that the value of $i$ is incremented first, and then the new value of $i$ is assigned to $c$.
Here is an example:
``` int i = 1; int c = i++;
printf("%d\n", i); // prints 2 printf("%d\n", c); // prints 1 ```
In this example, the value of $i$ is first incremented to 2, and then the new value of $i$ (2) is assigned to $c$. This means that $c$ now contains the value 1.
Here is another example:
``` int i = 1; int c = i++;
printf("%d\n", i); // prints 2 printf("%d\n", c); // prints 2 ```
In this example, the value of $i$ is first incremented to 2, and then the new value of $i$ (2) is assigned to $c$. However, the value of $i$ is still 2 after the expression is evaluated. This is because the value of $i$ is only incremented once, after the expression is evaluated.
I hope this helps!