High$-$level $($C$)$ function calls: Write the following functions. You may note that some of

the functionality is similar to what you wrote in Homework $11.$

$($a$)$ Write a function for determining if an input argument, a$,$ is divisible by $9.$ Hint: the

modulo operator $(\%)$ gives the remainder of an integer division. For example, $21\%9$

$=3($because the integer division has a remainder of $3$: $21/9=2$ R $3).$ The function

should return $1$ if the input argument is divisible by $9.$

Here is the start of the function:

int isDiv$9($int a$)\{$

$//$ function body goes here.

$\}$

$($b$)$ Write a function to calculate the factorial of an input argument, n$.$ It should return n$!$

For example, $5!=5*4*3*2*1=120.$

$($c$)$ Write a function called curve that adds $15$ to every entry of an array. Here is the

start of the function.

void curve$($int scores$[],$ int size$)\{$

$//$ function body goes here.

$\}$

$$ scores is the base address of the array

$$ void means that function does not return a value.

$$ size is the number of entries in the scores array.