Before the reversion of the province of Hong Kong from British to mainland Chinese rule, Cal, a citizen of California, entered into a contract with Hongko, a Hong Kong corporation. After reversion, mainland Chinese officials replaced a number of judicial institutions established by the British with judicial institutions preferred by the Communist Party. Later, during Communist Party rule, Cal brought an action against Hongko for breach of contract in California. Hongko moved to dismiss. Cal's best argument against dismissal is that --
A) The contract was made before the change in jurisdiction
B) Mainland China's jurisdiction doesn't apply in California
C) California law supersedes mainland Chinese law
D) Hongko is still obligated under British legal principles