$5.$ Which of the following regular expressions describe the language over the alphabet

$\{$a$,$b$\}$ that consists of all strings that contain at least one $\text{'}$a$\text{'}.$ a$)$ b$*$aa$*$b$*$

b$)$ b$*$a$($a$*$b$*)*$

c$)$ b$*$ab$*$a$*$b$*$

d$)$ none of the above