Select all the examples of intense/vigorous exercise activities.

Vigorous exercise activities are typically characterized by a high level of intensity that elevates the heart rate significantly and involves substantial energy expenditure. Racquetball is a perfect example of such an activity as it requires quick movements, agility, and involves intense bursts of speed and coordination. The nature of the sport demands high levels of effort, which makes it a vigorous exercise that can boost cardiovascular fitness and improve overall physical performance.

In contrast, the other activities listed do not meet the criteria for intense or vigorous exercise. Walking at a normal pace is generally considered low to moderate intensity. Yoga varies in intensity but often focuses more on flexibility and strength rather than cardiovascular fitness and does not usually elevate the heart rate to the same extent as vigorous activities. Gardening can also involve physical effort but typically does not have the sustained intensity required to be classified as vigorous exercise. Thus, while they can be beneficial for health, they do not match the vigorous exertion associated with racquetball.