I am not really sure but you can get the answer from it :
They discovered a fundamental mechanism of how proteins protect chromosomes while DNA is being copied (a process called DNA replication), which relies on a protein called RPA. Cells have a limited amount of this protein, which they use as 'band aids' to protect the DNA temporarily during replication.
The correct answer is tick on a dog.
The parasitic relationship can be defined as the relation in which one organism feeds on the other organism for their nutritional purpose. It can also harm the other organism by any means. Here, tick on the dog is dependent on the dog for its nutritional requirement. This is an example of parasitic relationship between dog and tick.
cyclins are proteins that regulate the time of the cell cycle in eukaryotic cells.
God bless!