Answer :
Final answer:
The Impressionists were able to paint in the Plein air technique of painting because of the invention of portable tin paint tubes.
Explanation:
The Impressionists were able to paint in the Plein air technique of painting because of the invention of the portable tin paint tubes. These tubes allowed artists to easily transport and store their paint, making it more convenient to paint outdoors. Prior to this invention, artists had to mix their paint on-site, which was not practical for outdoor painting.
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