This question tests for modifying phrase.
What is a modifying phrase? A modifying phrase has to be placed next to the noun or pronoun it is intended to modify. A modifying phrase that violates this rule is called a 'misplaced modifier'.
Let's keenly observe the options below.

Option A - incorrect
'Paul Gauguin' which is supposed to be the subject of the sentence is not properly placed. Also, 'WHERE' is supposed to come after 'TAHITI' which is supposed to act as a modifier.

Option B - incorrect
'Paul Gauguin' is supposed to act as the subject because the action is being performed on him. Meaning it should be placed at the subject level.

Option C - incorrect
In this option, the modifier modifies the wrong word 'years' instead of the actual subject which is 'TAHITI'

Option D - correct
In this option, the subjects are correctly modified. That is, where life was slow and relaxed correctly modifies Tahiti.
Also, had difficulty readjusting to the hectic pace of Paris upon his return correctly modifies Paul Gauguin. This is parallelism in right order.

Option E - incorrect
This option suffers from a big grammatical error and illogical construction. i.e upon returning to Paris because of the hectic pace