Answer:
Option B November 13th
Explanation:
The credit period begins from the day the invoice was received which is November 13th. Though we legally don't owe seller as he has not fulfilled his share or delivered consideration but if he is offering a contract that if you pay me within 30 (say) days we will give you 2% discount which means the consideration is early payment and in this contract the date starts from date of invoice received. So we will have to pay our supplier within 30 days starting from November 13, if we desire a 2% profit.