$$1\times 2\times 3\times 4\times 5\times (2\times 3)=2\times 4\times 2\times (1\times 3\times 5\times 3)=16\times 45$$. 
The greatest odd factor of the product $$1\times 2\times 3\times 4\times 5\times 6$$ is． 
[A] $$5$$ 
[B] $$15$$ 
[C] $$45$$ 
[D] $$75$$ 