You will be given a definition of a task first, then some input of the task.
In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.

Question: Who was the 2nd Earl of Lancaster's father-in-law? Passage:The House of Lancaster was the name of two cadet branches of the royal House of Plantagenet. The first house was created when Henry III of England created the Earldom of Lancasterfrom which the house was namedfor his second son Edmund Crouchback in 1267. Edmund had already been created Earl of Leicester in 1265 and was granted the lands and privileges of Simon de Montfort, 6th Earl of Leicester, after de Montfort's death and attainder at the end of the Second Barons' War. When Edmund's son Thomas, 2nd Earl of Lancaster, inherited his father-in-law's estates and title of Earl of Lincoln he became at a stroke the most powerful nobleman in England, with lands throughout the kingdom and the ability to raise vast private armies to wield power at national and local levels. This brought himand Henry, his younger brotherinto conflict with their cousin Edward II of England, leading to Thomas's execution. Henry inherited Thomas's titles and he and his son, who was also called Henry, gave loyal service to Edward's sonEdward III of England.
Links: a. Edward III of England b. Thomas, 2nd Earl of Lancaster c. Henry of Grosmont, 1st Duke of Lancaster d. Earl of Lancaster
Output:
b