Step 1: Eliminate the distractors first:
Gide/Rist (economic historians) and Henney are not associated with stratification theory, so they can be ruled out immediately.
Step 2: Compare the remaining two:
Between Marx and Engels, it is Marx whose name is attached to the concept and vision of the classless, communist society in the Marxist tradition, even though Engels was his co-author on related works.
Final Answer:
The correct choice is Marx.