During the 15th century , which two european countries began sea voyages of exploration

a true

explanation:

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.

the tariff was created to protect industry in the northern part of the united states. industries in the north were being driven out of business by imported goods that were priced at a low rate. the goal was to protect these industries   by taxing the goods.

i believe the correct answer is option b. most eastern european nations joined nato.

though i could be wrong, option d. the eastern european nations were granted complete independence, would be another choice.

hope this ! : )