When using advanced filtering, leaving a cell empty in the criteria range will return which of the following?

Before a command is echoed on the console, where must it first pass through?

A. STDOUT B. STDIN C. STDERR D. STDDEV

The ____ function returns a nonzero number if the character is a letter; otherwise returns a zero.

A. isupper(char) B. islower(char) C. isdigit(char) D. isalpha(char)