To solve this problem, we need to understand the types of errors in measurements.$\\$• Instrumental errors: These arise from imperfections in the measuring instruments.$\\$• Personal errors: These are due to human mistakes, such as reading a scale incorrectly.$\\$• Least count errors: These occur due to the limitations of the measuring instrument's smallest division.$\\$• Random errors: These are unpredictable fluctuations that can occur due to various factors,$\\$ such as changes in temperature, voltage supply, or other environmental conditions.$\\$The question specifically mentions errors due to unpredictable fluctuations in temperature and voltage supply.$\\$Such errors are categorized as random errors because they are not systematic and cannot be easily predicted or corrected.$\\$Therefore, the correct option is 4: Random errors.