The answers are: A, B, D, E and F, or every answer except C.
a the sale of used goods
The sale of used goods are not included in GDP, as this would amount to double counting.
b payment of under-the-table wages - We cannot include this is GDP because the government does not have access to the information.
d harmful economic side effects like pollution - This is not measured as a loss to GDP, although it would be a more realistic figure if it was.
e illegal drugs like marijuana - For the same reason as B, this is not included.
f goods that were produced outside our domestic borders - The measure is called Gross Domestic Product, which means wealth that is produced domestically.
All answer except C are correct.