Question

where do scientists find the evidence about past atmospheric conditions in ice cores?
through the composition of ancient snow
all these are correct
by measuring the thickness of each layer

Explanation:

Ice cores contain annual layers of snow that accumulate over time. The composition of ancient snow within ice cores can reveal the chemical makeup of the past atmosphere, such as the types and amounts of gases present. Measuring the thickness of each layer can also provide information about past climate conditions like precipitation levels and temperature, which are related to atmospheric conditions.

Answer:

B. All these are correct