High impact exercises.

are always high intensity
are always moderate intensity
can be any intensity level
none of the above

Explanation:

Exercises can be high impact or low impact. The basic definition of high impact exercise refers to those movements with both feet off the ground at the same time, like running or jumping jacks. Nowadays, most popular high impact training program is CrossFit, which its majority activity is high impact.

So, as you can see, the definition of this type of exercises don't involve intensity, because it can be high intensity or low intensity, they only characteristic to be high impact is that feet leave the ground at the same time.

In addition, these type of exercises should be considered by people who already have a fitness experience, or those without overweight and obesity, because it can damage joints and cause pain.

sadly i believe the answer is d