किसी वस्तु की एक अतिरिक्त इकाई के उपभोग के कारण कुल उपयोगिता में होने वाले परिवर्तन को क्या कहा जाता है?

Giffen goods are special inferior goods for which:

The price of coffee increases due to a supply shock caused by bad weather. As a result, consumers purchase less coffee and substitute it with tea, which is cheaper. Which economic concept is being illustrated in this sce nario?