 has only the prime divisors
 has only the prime divisors  and
 and  .
Every divisor of
.
Every divisor of  is therefore of the form
 is therefore of the form  ,
where
,
where  and
 and  are elements of {0,1,2,3}.  Since there
are
 are elements of {0,1,2,3}.  Since there
are  choices for
 choices for  and
 and  choices for
 choices for  , there are
, there are  divisors of
divisors of  .  That isn't necessary to know.  But
in the product of all
.  That isn't necessary to know.  But
in the product of all  divisors of
 divisors of  ,
,  or
or  , and
, and  or
 or  occur exactly
 occur exactly  times each.
Since
 times each.
Since  and
 and  both occur
 both occur  times each in the product
of all divisors, the product of the divisors must be
 times each in the product
of all divisors, the product of the divisors must be
 , choice a)
Edwin
, choice a)
Edwin