Company A, which is a Singapore company, concluded a sales of goods contract with Company B, which is a German company. The contract was signed on 30 November 2019. Under the contract, Company B, as the seller, agreed to deliver a certain amount of sheet iron rolls (the goods) to Company A, as the buyer, on or before 30 June 2020. The contract also specified that the United Nations Convention on Contracts for the International Sale of Goods (CISG) is the governing law of the contract.

Due to the outbreak of COVID-19, Company B was only able to deliver 50% of the goods to Company A on 30 June 2020. Company B requested for an extension of the delivery date and promised to deliver the rest of the goods on or before 31 December 2020. Company A agreed for the extension, but Company B failed to deliver the rest of the goods on 31 December 2020 due to a new wave of COVID-19 in Europe.

a) Based on your understanding of relevant provisions under the CISG, indicate three (3) possible remedies for Company A.

b) Advise one (1) possible defence for Company B under the CISG.