Why the status of taiwan is disputed

The Political and legal status of Taiwan (or the Taiwan Issue, Mainland Issue or Taiwan Strait Issue as referred to by the Republic of China) hinges on whether the island of Taiwan and Penghu should become unified with the territories of Mainland China under the rule of the Republic of China (ROC); become unified with the territories of Mainland China under the rule of the People's Republic of China (PRC); declare independence to become the Republic of Taiwan; or maintain the status quo of Cross-Strait relations that the PRC has incomplete Succession of states of the Chinese state in Mainland China, and the ROC relocates to the control of Taiwan and the surrounding islands in the remanent of the Chinese Civil War, with no peace accord nor truce to be negotiated between the two sides or any third parties to be involved after the Cold War.

In 1945, the ROC took control of Formosa (Taiwan), the Pescadores (Penghu) and other nearby islands, under the direction of the Supreme Commander of the Allied Powers.[1] In September 1952, Japan officially renounced its right to Taiwan in the Treaty of San Francisco without explicitly stating the sovereignty status of Taiwan, and hence some people regard that the sovereignty of Taiwan is still undetermined.

In addition, the situation can be confusing because of the different parties and the effort by many groups to deal with the controversy through a policy of deliberate ambiguity. The political solution that is accepted by many of the current groups is the perspective of the status quo: to unofficially treat Taiwan as a state and at a minimum, to officially declare no support for the government of this state making a formal declaration of independence. What a formal declaration of independence would consist of is not clear. The status quo is accepted in large part because it does not define the legal or future status of Taiwan, leaving each group to interpret the situation in a way that is politically acceptable to its members. At the same time, a policy of status quo has been criticized as being dangerous precisely because different sides have different interpretations of what the status quo is, leading to the possibility of war through brinkmanship or miscalculation.[2]

You can google it. the answer is d. international recognition