instruction:
You are given a question. You need to detect which category better describes the question. A question belongs to the description category if it asks about description and abstract concepts. Entity questions are about entities such as animals, colors, sports, etc. Abbreviation questions ask about abbreviations and expressions abbreviated. Questions regarding human beings, description of a person, and a group or organization of persons are categorized as Human. Quantity questions are asking about numeric values and Location questions ask about locations, cities, and countries. Answer with "Description", "Entity", "Abbreviation", "Person", "Quantity", and "Location".
question:
What is a bone marrow transplant ?
answer:
Description


question:
What have you not let a tennis ball do if you volley ?
answer:
Description


question:
What engineer invented the pull-tab can ?
answer:

Person