In this example, it says, "Label the following unsaturated fatty acids based on Omega classification." So, with Omega, we're looking at the methyl group in each one, and all we have to do is count to see how long it takes us to get to the double bond.
So for A, we count 1, 2, 3, 4, 5, 6. We had to get to the 6th carbon to get to our double bond, making this an Omega 6 Fatty Acid. For the next one, let's count. Here's 1, 2, 3, 4, 5, 6, 7, 8, 9. In this one, we have a new type of omega that we haven't seen yet. This is an Omega 9 fatty acid, but the process is still the same. The omega carbon is the methyl carbon, the carbon at the end. Count from the omega carbon to the double bond, seeing how long it takes us to get there, what carbon do we land on. That tells us the type of omega classification. So, for option A, we have an Omega 6 fatty acid, and then for option B, we have an Omega 9 fatty acid.