The Law of Superposition allows us to determine: a
which rock layers are the oldest
b
the relative age of layers of rocks and the fossils in them
c
the exact or absolute age of rock layers
d
a and b are correct

d . a and b are correct

Explanation:

The law of superposition allows us to determine the age of rock layers and also that of the fossils within them.

The law of superposition states that "in an undeformed sequence of strata, the oldest rock layer is at the bottom and the youngest is on top".

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.