Consider the set of divisors D12={1,2,3,4,6,12}D_{12} = \{1, 2, 3, 4, 6, 12\}D12={1,2,3,4,6,12} and D18={1,2,3,6,9,18}D_{18} = \{1, 2, 3, 6, 9, 18\}D18={1,2,3,6,9,18}. Identify the symmetric difference D12ΔD18D_{12} \Delta D_{18}D12ΔD18.
{4,9,12,18}\{4, 9, 12, 18\}{4,9,12,18}
{1,2,3,6}\{1, 2, 3, 6\}{1,2,3,6}
{4,6,9,12,18}\{4, 6, 9, 12, 18\}{4,6,9,12,18}
{1,2,3,4,9,12,18}\{1, 2, 3, 4, 9, 12, 18\}{1,2,3,4,9,12,18}