Correct option is B. A discovery in New Jersey actually contributed to the
early economic development of America and, in 1714, a worker uncovered a green rock containing copper.
Here, the use of conjunction 'and' is incorrect as it creates a kind of distortion which seems as if we are talking about two different things: rather then linking the two parts of the sentence, 'and' further disconnects it.
"When" seems better than "And". It clearly indicates the mentioned time. Thus B is the correct answer.
To learn more about copper from given link
brainly.com/question/24856041
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