Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: Royal Canin Feline Health Nutition Medium Adult 7 Dry Dog Food
Product description: Medium-sized dogs are famous for their energy, and were historically working dogs. Whether your medium dog is an indoor companion or spends time hunting outdoors, Royal Canin MEDIUM formulas help these dogs maintain natural defences throughout their life, while providing the balanced energy the medium dog needs to maintain a healthy weight.
Product feature: Adapted Content Of Nutrients To Help Maintain Vitality In Medium Breed Dogs During The First Stage Of Aging. Contains An Exclusive Complex Of Antioxidants To Help Support Cellular Health., Helps Promote Good Digestibility With An Exclusive Formula Including Very High Quality Protein And A Balanced Supply Of Dietary Fiber., This Formula Contains Nutrients That Help Support Healthy Skin And Coat. Enriched With Epa-Dha., Satisfies The Appetite Of Medium Breed Dogs With Carefully Selected Aromas., For medium breed dogs from 7 to 10 years old, Adult target weight: 21-55 lb
Product price: $19.79
Product brand: Royal Canin
Target attributes: Life Stage
Answer: attribute: life stage
value: adult
source: product feature
attribute: life stage
value: adult
source: product title