Check which of the following code segment will generate a memory error $($ if any$)?$

class Hello $\{$

public:

Hello$()$;

Hello$($const Hello& other$)$;

Hello$($int$*$ other$)$;

Hello$()$;

private:

int$*$ data;

$\}$;

$//$ Default Constructor

Hello: :Hello$()\{$data $=$ new int $[4]$; $\}$

$//$ Copy Constructor

Hello: :Hello$($const Hello& other$)\{$

data $=$ new int $[4]$;

$\}$

$//$ User define constructor

Hello: :Hello$($int$*$ other$)\{$

data $=$ other;

$\}$

$//$ Destructor

Hello: : Hello$()\{$delete$[]$ data; $\}$

int main$()\{$

Hello a;

Hello $b=a$;$\frac{,}{\frac{?}{?}}$ statement $x$

return $$;

$\}$