$9.$ A string literal in Python must be enclosed in$1.$ parentheses$\mathrm{.}2.$ single$-$quotes$\mathrm{.}3.$ double$-$quotes$\mathrm{.}4.$ either single$-$quotes or double$-$quotes$\mathrm{.}10.$ Short notes placed in different parts of a program explaining how those parts of the program work are called$1.$ comments$2.$ reference manuals$3.$ tutorials$1534.$ external documentationIl. A$($n$)$makes a variable reference a value in the computer's memory$\mathrm{.}1.$ variable declaration$2.$ assignment statement$3.$ math expression$4.$ string literal$12.$ This symbol marks the beginning of a comment in