Definition: Compose a new way to ask the same question. The new question must be asking the exact same thing as the original question does. Without any other information, you should be able to tell that the original question and the new question are the same. Preserve bracketed phrases in your new question. You can change the rest of the question provided the above requirements are satisfied. The new question must have a natural, fluent formulation, as if it were composed by a native English speaker. You will be given three pieces of information to help you create better questions. Those are: "Answer": the answer to the question, e.g., "Honolulu". "Answer Type": the type of the answer, e.g., "Location". "Auxiliary Information" is a detailed description of some concepts mentioned in the question, if any.
Input: original question: Which unit of charge is used in a measurement system that has the luminous flux units of [Lumen]? 
answer: coulomb
answer type: Unit of Charge.
auxiliary information: The lumen is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux measurements indicate the total power of all electromagnetic waves emitted, independent of the eye's ability to perceive it. Lumens are related to lux in that one lux is one lumen per square meter. The lumen is defined in relation to the candela as 1 lm = 1 cd‚ãÖsr. A full sphere has a solid angle of 4œÄ steradians, so a light source that uniformly radiates one candela in all directions has a total luminous flux of 1 cd √ó 4œÄ sr = 4œÄ cd‚ãÖsr ‚âà 12.57 lumens.

What is the unit of charge in the measurement system that uses [Lumen] for luminous flux units?