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: Dell Latitude E5400 Laptop - Core 2 Duo 2.0ghz - 2GB DDR2 - 120GB HDD - DVD+CDRW - Windows 8.1 64bit
Product description: Dell Latitude E5400 laptop installed with Windows 8.1 64bit. Intel Core 2 Duo 2.0GHZ with 2GB DDR2 RAM. Laptop comes with a 120GB hard drive and DVD+CDRW combo drive. It includes a 14.1" display, AC Adapter, Charger, and battery. The E5400 also includes 802.11g wireless WiFi, FOUR USB 2.0 ports, VGA out, speaker and headphone ports, S-Video Out, Firewire port, 10/100/1000 ethernet, and 30 day warranty.
Product feature: Intel Core 2 Duo 2.0GHz, 2GB RAM / 120GB Hard Drive, DVD+CDRW, 14.1" display, Windows 8.1 64bit
Product price: $128.98
Product brand: Dell
Target attributes: Refresh Rate
Answer: attribute: refresh rate
value: None
source: None