Final answer:
Encyclopedias are viewed as tertiary sources because they summarize information from primary and secondary sources and guide further research through their bibliographies.A or b is the correct option.
Step-by-step explanation:
Encyclopedias are often viewed as tertiary sources because they review a topic and usually include bibliographies of primary and secondary sources consulted.
These tertiary sources are essential tools that provide summaries or digests of information from both primary and secondary sources. They serve as a starting point for research, offering a broad overview of a topic and directing researchers to more specific sources through their bibliographies.
It is important to note that while they condense information, tertiary sources like encyclopedias alone cannot support claims sufficiently due to their summary nature. However, their role in providing general context and access to primary and secondary sources is invaluable in the research process.