The Earth is about 4.6 billion years old. However, the oldest sea floor is only about 180 million years old. What do you think is the reason for this? (Hint: Remember that new seafloor is constantly being created, but the Earth is not getting bigger with time.)

The seafloor is only 180 million years old due to the process of subduction. The floor of the sea's tends to get colder and denser with the passage of time. At a certain time, the seafloor becomes so dense that it sinks in the upper mantle. The Earth's crust cannot undergo this process and hence has oldest rocks. We can say that the seafloor is less than 180 million years old because it is typically recycled back into the mantle of the Earth.

answer; /// i believe the correct answer is (thrombocytopenia); (a)

hey, i believe your answer would be d. sugar ribose and the base uracil. i believe this is the answer, because rna consists of sugar ribose, adenine, guanine, cytosine, and uracil.

your first option is incorrect, because that's dna. where it consists of sugar deoxyribose, adenine, guanine, cytosine and thymine.

your second option is also incorrect, this is because sugar deoxyribose is in dna, and uracil is in rna. these two do not make sense together.

your third option being incorrect, because sugar ribose is in rna, but not the base of thymine. rna consists of uracil, not thymine.

lastly your fourth option being correct! this answer is correct, because both sugar ribose, and the base uracil are in rna! ~

answer is d. sugar ribose and the base uracil.