Read the following passage and mark the letter A, B, C, or D on your answer

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 16 to 20.

Dressing up in costumes and trick-or-treating are popular Halloween activities, but few probably (16) ______ these lighthearted fall traditions with their origins in Samhain, a three-day ancient Celtic pagan festival.
For the Celts, who lived during the Iron Age in what is now Ireland, Scotland, the U.K. and (17) ______ parts of Northern Europe, Samhain (meaning literally, in modern Irish, “summer's end”) marked the end of summer and kicked off the Celtic new year. Ushering in a new year signaled a time of both death and rebirth, something that was doubly symbolic because it (18) ______ with the end of a bountiful harvest season and the beginning of a cold and dark winter season that would present plenty of challenges.
Eventually, Halloween became more popular in secular culture than All Saints' Day. The pagan-turned- Christian practices of dressing up in costumes, playing pranks and handing out offerings have evolved into popular traditions even for those (19) ______ may not believe in otherworldly spirits or saints. (20) ______, whether Halloween celebrants know it or not, they’re following the legacy of the ancient Celts who, with the festival of Samhain, celebrated the inevitability of death and rebirth.