This is a really tricky question because all of them are possible
A - Select the contract field Disable Amendment Co-Term to prevent amendment quotes on the contract from inheriting the contract’s end date. See https://help.salesforce.com/s/articleView?id=sf.cpq_amend_subs_mult_end_dates.htm&type=5
B - Adjust the quantity of the quote lines from your original quote, apply discounts, or add new products, and then save your changes.
You can amend assets to have a lower quantity only if their related product record has an asset amendment behavior of Allow Refund. See https://help.salesforce.com/s/articleView?id=sf.cpq_amend_contracts.htm&type=5
C - An obvious valid answer, see the previous links
D - it's equivalent to B, you can maintain the original discounts

Correct Answers: C & D.

correct Ans = C and D