Stupas are Buddhist commemorative burial mounds. They are structures that are built in honor of the Buddha or other revered figures in Buddhism. To answer this question, we can start by understanding what stupas are in general. Then, we can infer that Buddhist monasteries and shrines might be incorrect because although they are also important structures in Buddhism, they are not specifically referred to as stupas. Similarly, war memorials and Asoka's principles for moral law are unrelated to the concept of stupas. Thus, the correct answer is "Buddhist commemorative burial mounds."
