D. Stream#forEachParallel() Here's why the other options are not ideal for concurrent iteration: A. for loop and b) while loop: These traditional loop constructs are not inherently thread-safe. If multiple threads try to modify the collection concurrently while iterating using these loops, you might encounter race conditions and data corruption. C. Iterator#next() : While Iterator provides a way to iterate over a collection, it doesn't guarantee thread safety. It's essential to use the collection's appropriate methods or concurrent collection implementations for safe concurrent iteration. Stream#forEachParallel(): This method belongs to the Java Streams API and is specifically designed for parallel processing of elements in a collection. It leverages multiple threads to process elements concurrently, potentially improving performance for large collections. It's important to note that forEachParallel() is used for side effects on each element (like printing) and not for collecting results into a new collection. If you need thread-safe collection, consider using collect() with appropriate collectors. Thread Safety Considerations: While forEachParallel() enables concurrent iteration, it doesn't guarantee the order in which elements are processed. The order might be non-deterministic. 47/97 If your operations within the loop require maintaining order or involve modifications to the original collection, you might need additional synchronization mechanisms or use concurrent collection implementations like CopyOnWriteArrayList.