Citral and camphor are both 10-carbon odoriferous natural products made from the joining of two isoprene units

Question:

Citral and camphor are both 10-carbon odoriferous natural products made from the joining of two isoprene units plus the addition of a carbonyl functional group. Shown below are their chemical structures. Find and circle the two isoprene units in each of these molecules.

CH3 H. CH3 H,C Isoprene (2-methyl-1,3-butadiene) Camphor Citral