In a function call, what is the operator, and what are the operands?

I am trying to understand some basics of C. KRC's The C Programming Language says

A function call is a postfix expression, called the function designator, followed by parentheses containing a possibly empty, comma-separated list of assignment expressions (Par.A7.17), which constitute the arguments to the function.

1. In a function call, what is the operator, and what are the operands?

   Is () the operator?

   Is the function name an operand?

   Are the arguments inside () operands?

2. Is a function designator a synonym of a function call?

Thanks.