Which of these could not have occurred until the postclassical era?
o
a. a west african ruler converts to islam.
o
b. a byzantine merchant sells goods in india.
o
c. a persian general decides to attack a greek city-state.
o
d. a chinese ruler sends an ambassador to europe.

i think your answer there is c

radioactive dating, also known as  radioisotope dating  is a process that in  estimating the approximate  age  of  rocks. these data can be analyzed from  the studies dealing with the  decay of the radioactive elements that are present in these rocks. in nature, there are a few types of materials or atoms which are quite unstable and they spontaneously decay or breakdown to form other kinds of atoms.

thomas jefferson is the answer