Suppose $A$ is an abstract class, $B$ is a concrete subclass of $A,$ and both A and $B$ have a no$-$arg constructor. Which of the following has errors $($either a compile error or a runtime error$)?$

$A[]ab=$ new $B[10]$;

$A[]aa=$newA$[10]$;

$Bb=$ new B$()$;

$B[]bb=$ new $B[10]$;

$Aa=$new $A()$;

$A$ a$=$new B$()$;