Weights from the site of mohenjodaro in pakistan were found to be multiples of intigers such as 1, 4, 8, 64, 320, and 1600, meaning they can be seen as representing a

Constant unit of mass

Explanation:

The Mohenjo Daro Weights are a series of standard units of weight used by the early inhabitants of the Indus Valley Civilization, around the years 2600 - 1700 BCE, in what is today Pakistan. These weights were made of different kinds of rock, such as limestone, agate, and chert. The smallest unit found, weighing approximately 0.856 grams, was apparently used as a base unit. Each unit from this one was first double the weight of the previous one: 1, 2, 4, 8, 16 and so on, up to 160. From this one on, the next set of weights proceeded on a hexadecimal base - in other words, as multiples of 16: 320, 640, 1600, 6400 and so on, up to 32,000. These weights demonstrate the use of very sophisticated constant units of mass, and were used by Indus Valley merchants to buy and sell their merchandise, ranging from precious minerals to food grains.

d is the right answer

there was a king, priests, and peasants.