I got D as well, but I suck at these so it was largely a guess. My logic:
Customer - transaction = One to Many. One customer can make many transactions, but one transaction cant have many customers.
Transaction - video = Many to one. Many barcodes can be used in the transaction process (for many videos), but each only link to one video barcode.
Video - Movie = Many to One? This is the only possible answer from my deduction. However, I would have assumed the correct answer would be Many to Many (which isn't up there).
Would love confirmation and suggestions.