Definition: 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.
Input: Question: What type of organisms usually form the rock that the original 1857 asylum building is made from? Passage:The original 1857 asylum building (now the Nowotny Building) is a two-story Italianate structure of rough limestone with red brick detailing. The main facade features five sets of paired windows with limestone sills framed in brick and topped with brick segmental arches. The corners are reinforced with brick quoins, and a wide first-story portico extends to both sides of the main entry. A brick cornice marks the roofline, above which the gray metal roof is punctuated by an octagonal Italianate dome. The building was designed and built by Abner H. Cook, an Austin architect who had recently designed the Texas Governor's Mansion.
Links: a. Portico b. Italianate architecture c. Limestone d. Texas Governor's Mansion
Output:
c