The Cambrian Explosion resulted in the evolution of the first representatives of most animal phyla. The second option among all the options given in the question is the correct option. The Cambrian Explosion is also known as Cambrian Radiation and it took place around 542 million years ago.
State department
Their responsibilities also include
Protecting and assisting U.S. citizens living or traveling abroad;Assisting U.S. businesses in the international marketplace;Coordinating and providing support for international activities of other U.S. agencies (local, state, or federal government), official visits overseas and at home, and other diplomatic efforts.Keeping the public informed about U.S. foreign policy and relations with other countries and providing feedback from the public to administration officials.Providing automobile registration for non-diplomatic staff vehicles and the vehicles of diplomats of foreign countries having diplomatic immunity in the United States
Over and over again he rehearsed it in wearisome <em><u>repetition</u></em><em><u> </u></em>until it had assumed a certain and almost invariable form.
Hence the answer is :
<h3>(c) Repetition </h3>