$$2016=2\times2\times2\times2\times2\times3\times3\times7$$; there are $$3$$ different primes. 
How many different primes are in the prime factorisation of $$2016$$? 
Options:
1) $$3$$ 
2) $$4$$ 
3) $$7$$ 
4) $$8$$ 