Answer:
b. Wolfram Alpha
Explanation:
A specialty search engine can be defined as a type of database query engine which searches for informations and indexes them based on a particular content, subject or focus such as location, topic, government, industry etc. A specialty search engine is different from the general-purpose search engines such as Bing, Google or Yahoo because it gives results that are tailored or more relevant to a particular user.
Wolfram Alpha is an example of a specialty search engine. A Wolfram Alpha is an answer search engine which gives answers to specific questions such as computational, arithmetic, geometric mathematics or calculus.
Also, note that a specialty search engine is commonly referred to as a topical or vertical search engine.
