the answer is D. Some of the world’s highest waterfalls can be found in three countries: Venezuela, South Africa, and Peru.
a colon in a sentence means the auther can end the sentence with a period if he wanted and the sentence would still be correct.
in this case the sentence could be, "Some of the world’s highest waterfalls can be found in three countries."
this still looks and sounds correct and is a fully functioning sentence.
! “And the kings of the earth, who have committed fornication and lived deliciously with her,
Shall bewail her, and lament for her, when they shall see the smoke of her burning,
Standing afar off for the fear of her torment, saying, Alas, alas, that great city Babylon,
that mighty city! For in one hour is thy judgment come .
The author fears the day of judgement .