Instruction: First, identify the target attributes from the provided list. Then, scan the product title, description, feature, and brand to extract the values associated with each target attribute. Finally, create a list of dictionaries, each containing the extracted attribute, its corresponding value, and the source where it was found.

Input:
Product title: Lenovo C20 - 19.5" All-in-one (Intel Celeron N3050, 4GB, 500 GB HDD) F0BB007CUS
Product description: An All-in-One PC that the entire family will enjoy, the Lenovo C20 balances features and performance with an unbeatable price tag.
Product feature: Intel Celeron N3050 1.6 GHz, 4 GB DDR3, 500 GB 7200 rpm Hard Drive, 19.5-Inch Screen, Intel HD Graphics
Product price: $17.66
Product brand: Lenovo
Target attributes: Operating System
Answer: attribute: operating system
value: None
source: None