For the code shown below, the line numbers are added for your reference:

$1.$ def maybeAdd$($a $,$b $)$:

$2.$ for let in b:

$3.$ if let not in a:

$4.$ a$.$append$($let$)$

After the code above runs, which of the following can be concluded about a:

len$($a$)=$ len$($b$)+1$

len$($a$)=$ len$($b$)$

len$($a$)$ will be the same before and after the code runs

No correct anstver is shown.