Select from the following.
a). kalenchoes;
b). sun;
c). liver cancer;
d). black hole;
e). sea squirts;
f). layers of fat;
g). stars;
h). ocean;

Fact 1: If an object is black then that object absorbs all visible light. Fact 2: Black holes emit no light. Given the two facts above, what are not visible?
Answer:
d).