Which property describes the ability of film base not to be easily torn?

The ability of a film base not to be easily torn is best described by high tensile strength. Tensile strength refers to the maximum amount of tensile (stretching) stress that a material can endure before failure or breaking occurs. In the context of film production, a film base with high tensile strength will be durable and resistant to tearing or breaking under stress, which is vital for both handling and during the imaging process.

Other properties, while important in their own right, do not directly relate to tear resistance in the same way. Flexibility pertains to how much a material can bend without breaking, and while flexibility may contribute to the durability of the film, it does not specifically indicate its ability to withstand tearing forces. Dimensional stability refers to a material's ability to maintain its shape and size under varying conditions, which is significant for ensuring consistent image quality but not for its resistance to tearing. Low density relates to the weight of the material and does not correlate with its strength or capability to resist tearing. Therefore, high tensile strength is the most accurate descriptor of the film base's resistance to tearing.