Answer:
Both chemical and physical change
Step-by-step explanation:
Physically, the change in color is due to the addition and subtraction of pigments such as chlorophyll, carotenoids and anthocyanins
Chemically, the change results from the conversion of the pigments chemicals such as chlorophyll and anthocyanins product one form to another product.
From the article, it is noted that during the autumn, there is cooler weather and less sunshine due to shorter days, and hence the trees instead of relying on the sunshine for the production of plant food through photosynthesis, the trees absorbs the food stored in the leaf for storage and nutrition during the winter periods, in the process, chlorophyll, the substance that gives the leaves their green color, is broken down and the leaves changes color.
After the chlorophyll is broken down other chemicals present carotenoids and anthocyanins (formed by trapped sugar in leaves) provide pigments which gives the leave.