rj0001 wrote:I am a bit confused about why q39 would be a and not b since, b offers the smaller options for the methyl group (3,4,8) over option a which is (3,7,8)
Good point! However, we need to give the double bond the lowest possible numbering which means that it will be between carbon 1 (one of the bridgehead carbons) and carbon 2 (which starts counting towards the left of the molecule). Then when you count the positions of the methyl groups, (3,7,8) becomes the only possibility. Note that in the priority rules given in the passage, it can be seen that double bonds must be a higher priority than a methyl group.
If any of this remains unclear, please note that you have access to a free webinar next weekend to discuss any of these VR-1 Section 3 units. Good luck!