When did people begin to notice that coastlines of continents fit together like puzzle pieces? when satellites began taking pictures of Earth from space
when Alfred Wegener proposed the idea of continental drift
when early explorers traveled from Europe and Asia to the Americas
when geologists first started examining the fossil record of South America

The 1500s

Explanation:

the1500s

As early as the1500s map makers were beginning to notice that the individual continents fit together like pieces of a jigsaw puzzle. It wasn't until 1912 that Alfred Wegener first proposed an acceptable hypothesis (continental drift) as an explanation

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.