Dave's First Question: What Is the Downward-Pointing Pentagon on the Horizontal

Dave's first question: What is the downward-pointing pentagon on the horizontal ruler?

A) A tab stop marker, which is used to display the location of a tab stop.
B) A 'First Line Indent' marker, which is used to indicate the position at which paragraphs begin.
C) An object margin, which indicates the area outside or inside the object margin.
D) A tab selector, which displays the current alignment setting.