Instruction: Given the title, description, feature, price, and brand of a product and a set of target attributes, extract the value of each target attribute from the product information. Output the extracted value and the corresponding source (e.g., title or feature) denoting where the value is extracted.

Input:
Product title: AO Smith GVR-50 Residential Natural Gas Water Heater
Product description: AO Smith ProMax + Plus High Efficiency GVR-50 Water Heater Residential Nat Gas 50 Gal Tall Recovery 41 Gal @ 90 40,000 BTU Input .62 Energy Factor 10 Year Limited Warranty., AO Smith ProMax + Plus High Efficiency GVR-50 Water Heater Residential Nat Gas 50 Gal Tall Recovery 41 Gal @ 90 40,000 BTU Input .62 Energy Factor 10 Year Limited Warranty.
Product feature: Qualifies for most gas utility rebate programs, Energy Star Home Program, Features FVIR that protects against accidental ignition of flammable vapors, Green Choice gas burner, Piezo igniter for easy "no match" pilot ignition
Product brand: AO Smith
Target attributes: Type
Answer: attribute: type
value: 50 gal
source: product description