The correct structure of 2 ,   6 - Dimethyldec- 4 -ene is:

Step-by-step solution

In the given IUPAC name ene is the suffix, hence, there is a double bond at the 4th position of the longest chain. Parent chain name is dec, hence, there are 10 carbon in the longest chain and methyl substituents are attached at 2 and 6th positions.