What is the property of a metal that allows it to be beaten into thin sheets? 

Malleability 

The correct answer is option 2. Malleability.

The property of a metal that allows it to be beaten into thin sheets is called malleability. Malleability is the ability of a metal to deform under compressive stress, such as hammering or rolling, without breaking or fracturing. Metals that exhibit high malleability can be easily shaped into thin sheets or foils by hammering or rolling without undergoing significant damage. This property is essential in various manufacturing processes, such as metalworking, forging, and sheet metal fabrication. So, the correct answer is Malleability.