Final answer:
The Gray tube is the correct tube to use for measuring lactic acid. Hence the correct answer is B.
Step-by-step explanation:
The correct tube to use for measuring lactic acid is the Gray tube.
The gray-top tube, also known as the "lactic acid tube" or "anaerobic tube," typically contains an anticoagulant (sodium fluoride) and an inhibitor (potassium oxalate). This combination is suitable for preserving blood samples for the measurement of lactate (lactic acid) levels.
Lactate is often measured in the context of assessing metabolic function and is frequently analyzed in conditions such as sepsis, shock, or suspected metabolic disorders. The use of the appropriate tube is crucial to prevent changes in lactate levels that could occur if the sample is not properly preserved.