Which of the following is a common attachment for backhoe loaders?

Common attachments for backhoe loaders include augers, which are specifically designed for drilling holes in various types of soil. They are particularly useful for tasks such as setting fence posts, planting trees, or installing foundations. The auger attachment can easily be mounted to the backhoe's hydraulic system, allowing operators to effectively bore holes within a range of sizes and depths. This versatility enhances the backhoe loader's functionality, making it suitable for a wide range of construction and landscaping projects. The other options, while they serve specific purposes, are not typically associated with backhoe loaders; for instance, excavator booms, pile drivers, and bulldozer blades are designed for use with different types of heavy machinery and would not be compatible or practical as attachments on a backhoe loader.