Definition: In this task, you are given a passage and a question regarding that passage. You must determine whether or not the question is answerable from the given passage. If a question is answerable, output should be 'True', otherwise 'False'. You must not consider any other information that is not provided in the passage while labelling True or False.
Input: Passage: Instability troubled the early years of Kublai Khan's reign. Ogedei's grandson Kaidu refused to submit to Kublai and threatened the western frontier of Kublai's domain. The hostile but weakened Song dynasty remained an obstacle in the south. Kublai secured the northeast border in 1259 by installing the hostage prince Wonjong as the ruler of Korea, making it a Mongol tributary state. Kublai was also threatened by domestic unrest. Li Tan, the son-in-law of a powerful official, instigated a revolt against Mongol rule in 1262. After successfully suppressing the revolt, Kublai curbed the influence of the Han Chinese advisers in his court. He feared that his dependence on Chinese officials left him vulnerable to future revolts and defections to the Song. Question: Who was Kaidu's grandfather?

True