Answer: Option D.
Cyclins are proteins that regulate the cell cycle at molecular level.
Explanation:
Cell cycle refers to series of activities that take place in the cell leading to replication of DNA and division of cytoplasm to give two daughter cells. Cell cycle are regulated by a set of proteins called cyclins.
Cyclins are group of proteins the bind and activates cycling dependent kinases enzymes in order to control cell progression through the cell cycle.
Explanation:
Brine pools are sometimes called sea floor "lakes" because the dense brine does not easily mix with overlying seawater. The high salinity raises the density of the brine, which creates a distinct surface and shoreline for the pool. When submarines dive into brine pools, they float on the brine surface due to the high density
I swear it's the cell membrane.. I'm not sure though