Which source of information would offer the most reliable fact-based information about j. r.r. tolkien, the author of the lord of the rings trilogy? a)a biography entry on wikipedia b)a book published during tolkien's life c) a movie about the life of tolkien d) a book published last year about tolkein's life

The correct option is B.
The source of information, that would offer the most reliable fact-based information about the author is a book, that is written by the author himself. This type of source is called primary source. Information obtained from Wikipedia, movie and books published by other authors can only offer secondary information, which are not as reliable as information from primary source.

The primary source are those that came from the main person or the one who witnessed the said event. So the ource of information that would offer the most reliable fact-based information about J.R.R. Tolkien, the author of The Lord of the Rings trilogy is
B)A book published during Tolkien's life

The main academic skill is math