Select all the examples of moderate exercise activities.

Walking at a pace of 3½ miles an hour or quicker is indeed considered a moderate exercise activity. Moderate exercise is generally characterized by an intensity level that can noticeably elevate your heart rate but still allows you to carry on a conversation. This pace offers a good balance between sustainability and health benefits, making it accessible for many individuals looking to improve their fitness levels.

In contrast, running a marathon, sprinting, and weightlifting tend to fall under higher intensity categories. Running a marathon is an endurance activity typically associated with vigorous exercise, requiring substantial energy and physical endurance. Sprinting is also a high-intensity effort that primarily serves anaerobic fitness, which is beyond the moderate intensity level. Weightlifting can vary in intensity based on the weight used and the number of repetitions but can often be classified as more vigorous, especially when heavy weights are involved or when performed in a high-intensity circuit format.

Thus, walking at that specified pace clearly fits the criteria for moderate exercise, emphasizing the importance of understanding the different levels of physical activity in terms of their benefits and sustainability.