In Java, an identifier is a sequence of characters consisting of letters, digits, underscores, and dollar signs. It cannot start with a digit. Which of the following regex describes a java identifier?

$[$a$-$zA$-$Z$0-9\_$$$]+$

$[a-zA-Z_{\text{\$}}{]}^{**}[a-zA-Z0-9_{\text{\$}}]+$

$[a-ZA-Z_{\text{\$}}{]}^{**}$

$]=[9_{\text{\$}}$