Understand How an Array of Structures is Sent to a Function

/*
Write a program to understand how an array of structures is sent to a function 
*/

#include<stdio.h>

struct student {
        char name[20];
        int rollno;
        int marks;
           };
void display(struct student);

void dec_marks(struct student stuarr[ ]);

main( )
{
    int i;
    struct student stuarr[3] = {
                    {"Mary", 12, 98},
                    {"John", 11, 97},
                    {"Tom", 12, 89}
                    };
    dec_marks(stuarr);
    for(i=0; i<3; i++ )
        display(stuarr[i]);
}

void dec_marks(struct student stuarr[])
{
    int i;
    for(i=0; i<3; i++)
        stuarr[i].marks = stuarr[i].marks-10;
}

void display(struct student stu)
{
    printf("Name  - %s\t", stu.name);
    printf("Rollno  - %d\t", stu.rollno);
    printf("Marks  - %d\n", stu.marks);
}