Question 30 - Paragraph Comprehension Practice Test for the ASVAB

What is the best choice for the meaning of cavernous, as used in this passage?

The Library of Congress’ Law Library is a closed stacks library, which means that nearly 99% of its print collection is housed in compact shelving in cavernous underground storage rooms covering an area nearly the size of two U.S. football fields. Patrons desiring to review books held in the closed stacks simply submit an online request for them; requested materials are usually delivered to the Law Library Reading Room for use within approximately an hour.