Answer:
a. more than one pathway at the same time.
Explanation:
Basically, RTK (receptor kinase receptor) principally activate many different transduction pathways about 10 or more and many cellular response in living cells.Thus, its activates more than one signal transduction pathways at once, (compare to G-protein ), and with this mechanisms it aids in coordination of some aspects of cell growth and cell reproduction .
The answer is C barriers around mating
For Absolute dating they assign a numerical date to each rock layer studied
For relative dating they go Through geological dating and stratigraphy processes. Also, they use Uranium Dating.