Complex sentence: Author Christopher L. Hodapp asserts in his book "The Templar Code for Dummies" that Glastonbury Tor is one of the possible locations of the Holy Grail, because it is close to the monastery that housed the Nanteos Cup.
Split into simpler sentences: Author Christopher L. Hodapp asserts in his book "The Templar Code for Dummies" that Glastonbury Tor is one of the possible locations of the Holy Grail. This is because it is close to the location of the monastery that housed the Nanteos Cup.