The correct answer is D.) The British Government asked for help fighting German raiders in the waters around Japan. Japan also had territorial ambitions in the region.
Even though initially, Japan didn't want to have anything to do with the World War, after being asked for help by Britain, it couldn't refuse. Britain had always been a Japanese ally so they decided to help it out in the war. However, the reason for this wasn't only this altruistic - Japan wanted something in return. It wanted to be allowed to take over some territories in China, especially those which belonged to Germany. This is why Japan declared war on Germany in 1914.