The answer is; A.
Invasion literature imagines a war scenario where a country is under attack. It then analyses the capacity and capability of the country to repel the attack. This kind of literature was particularly popular during the ward war era when countries like Germany would invade other countries and threaten a shift in global power. The same invasion literature continues today between Russia and the United States (the two military superpowers) as they asses each other's readiness in case of a war between the two countries.