What is the role of 'foo' in the PHP statement function('foo');?

The document inspector displays both a red exclamation point and a(n) ________ button in the dialog box if it finds sensitive or personal information within a document

Fill in the blank(s) with correct word

A(n) ____________ works like a reference parameter, but the argument does not have to be set to a value before it is passed into the parameter.

a. parameter list b. named argument c. output parameter d. named constant