The passage of a cell through the stages of the cell cycle is controlled by protein kinases that phosphorylate many different proteins at appropriate times. what are these protein kinases called?
a. cyclins
b. cyclin-dependent kinases
c. cdk activating kinases
d. tyrosine kinases

A. Cyclins

Explanation:

Cyclins are group of related proteins and are the most important core cell cycle regulators. Each cyclin is associated with a particular transition or phase in the cell cycle and helps drive the events of that phase or period by partnering with a family of enzymes called the cyclin-dependent kinases (Cdks).

Cdks are kinases, enzymes that phosphorylate (attach phosphate groups to) specific target proteins. The apg acts like a switch, making the target  less active or to have more protein. When cyclin attaches to Cdk, it can activate the Cdk as a kinase and can directs also the Cdk to a specific set of target proteins. For example, G1/S cyclins send Cdks to S phase targets (e.g., DNA replication), while M cyclins send Cdks to M phase targets (e.g.,breakdown of the nuclear membrane ).

c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.

the last one: artificial selection/genetic engineering

plant breeding is modifying the genetic composition of the plant - but this isn't cloning (which is specifically introducing a gene into a genome). but you are artificially selecting for the phenotype that you want.

the second one is literally genetic engineering - the gene would have been cloned first and then inserted or genetically engineered into the new plant cell (the cotton).