Given two object references:

SimpleDate d$1=$ new SimpleDate $(10,08,2021)$;

SimpleDate d$2=$ d$1$;

Which of the following should be used to test if the object references $d1$ and $d2$ point to the same object?

d$1.$ sameAs $($d$2)$;

$d1==d2$

$d1=d2$

d$1.$equals $($d$2)$;