Which of these explain how ice cores can be used to correlate atmospheric makeup and climate changes over time?

A) As ice melts into water, the thermal expansion traps gases from the atmosphere that can later be analyzed

B)As ice forms, a latent heat is released from the ice. This causes carbon dioxide levels to increase in the atmosphere.

C) As snow packs freeze and build up gradually over time, gases from the atmosphere are trapped within the ice and can be analyzed.

D) As snow falls onto an existing glacier, methane is released and carbon dioxide is trapped, indicating the makeup of the atmosphere at a particular time period.

Answer is C according to Usatestpep

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."

the dna molecules have a negative charge because of the phosphate groups in their sugar-phosphate backbone, so they start moving through the matrix of the gel towards the positive pole. power is turned on and dna fragments migrate through gel (towards the positive electrode).

explanation:

d. organisms have cells with different shapes and functions.