Final answer:
The standards of measurement during the Middle Ages were often based on unconventional criteria like the length of the king's arm due to a combination of factors: lack of scientific knowledge, tradition and authority, and limited resources.
Step-by-step explanation:
The standards of measurement during the Middle Ages were often based on unconventional criteria like the length of the king's arm due to a combination of factors. First, there was a lack of scientific knowledge and understanding of standardized measurement systems. Second, tradition and authority played a significant role in shaping these standards, as the king's arm was seen as a symbol of power and legitimacy. Lastly, there were limited resources and infrastructure available for accurate measurement. Without the advanced tools and techniques we have today, people had to rely on what was readily accessible to them. Therefore, the correct answer is d) All of the above, as all of these factors contributed to the unconventional criteria used for measurement during the Middle Ages.