Which statement is correct?

a. The prevalent approach for indexing full-text documents is an inverted index.

b. SQL is well suited to query structured collections of records as well as unstructured data such as text.

c. It makes no sense to look at HTML markup when calculating the weight of a term to a page for web search.

d. Enterprise search technologies are strongly related to standard web search products and providers (e.g., Google), but aim to offer a series of tools that can be deployed and used externally such that an organization can expose itself to the outside world.