Answer:
The correct option is A. Australia and New Zealand signed the ANZUS Pact in 1951 with the United States to guarantee protection in case of military threats. The pact was a mutual defense agreement between the three countries, where they agreed to consult with each other and take action to meet common security threats in the Pacific region. This was especially important for Australia and New Zealand, who were concerned about the spread of communism in the region and potential threats from nearby countries such as Indonesia. The ANZUS Pact also helped to strengthen the relationship between the United States and its allies in the Asia-Pacific region.