An index fossil must be?

Question

a) older than 1 billion years.
b) smaller than other fossils around it.
c)larger than other fossils around it.
D) unique in its appearance.
pleases help someone i don't really know but my best guess is a)

Answer 1

my answer is incorrect it was D)

Answer 2

so is the wright answer D)?

Answer 3

An index fossil must be
A.
older than 1 billion years.
B.
unique in its appearance.
C.
larger than other fossils around it.

Answer 4

Which of the following is true about the age of rock layers and the age of the Earth?
A.
The Earth is older than any rock layer.
B.
The bottom layer in a sequence of rock layers is older than the Earth.
C.
The top layer in a sequence of rock layers is older than the Earth.