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: Apple MacBook Pro 15.4-Inch Laptop with Retina Display (NEWEST VERSION with UPGRADES) 2.0GHz Core i7 8GB 512GB Flash
Product description: A groundbreaking Retina display. All-flash architecture. The latest Intel processors. Remarkably thin and light 13-inch and 15-inch designs. Together, these features take the notebook to a place it's never been. And they'll do the same for everything you create with it. The 15-inch MacBook Pro with Retina display has the power to do even more amazing things. Fourth-generation quad-core Intel Core i7 processors provide the fastest performance ever in a MacBook Pro. Display 15.4-inch LED-backlit Retina display with IPS technology; 2880-by-1800 native resolution at 220 pixels per inch with support for millions of colors Processor 2.0 GHz quad-core Intel Core i7 (Turbo Boost up to 3.2 GHz) with 6 MB shared L3 cache Storage 512 GB flash storage Memory 8 GB of 1600 MHz DDR3L onboard Graphics Iris Pro Graphics (integrated, with 128 MB of embedded memory) Video Thunderbolt digital video output (native Mini DisplayPort output); compatible with DVI, VGA, and dual-link DVI output using optional adapters HDMI video output Audio Stereo speakers; dual microphones; headphone port; support for Apple iPhone headset with microphone; support for audio line out (digital/analog) Connections Two Thunderbolt ports (up to 20 Gbps) Two USB 3 ports (up to 5 Gbps)< OS X Mavericks includes: AirDrop AirPlay Dictation Gatekeeper Notification Center Facebook Integration Twitter Integration Multiple Display Support Finder Tabs and Tags iCloud iCloud Keychain Dashboard Mission Control Spotlight Search Safari Power Saver App Nap Power Nap Compressed Memory Built-in Sharing Built-in apps: iPhoto iMovie GarageBand Pages Numbers Keynote Maps iBooks Safari Mail FaceTime Messages Calendar Contacts Reminders Time Machine Photo Booth iTunes Game Center Preview Notes Mac App Store
Product brand: Apple
Target attributes: Screen Size
Answer: attribute: screen size
value: 15.4-inch
source: product title
attribute: screen size
value: 15.4-inch
source: product description