Task: Question Answering
Input (English): Question: The determination of mercury by the cold vapor generation technique is based on the reduction of mercury in acid solution and the entrainment of the elemental mercury obtained to the absorption cell for analysis by atomic absorption. The most commonly used reducers are: 
 Options:  <1> SnCl2, for inorganic mercury and Na BH4 for both organomercury compounds and inorganic mercury. <2> Citrate, both for inorganic mercury, and organomercuriales. <3> Glutathione, especially suitable for all mercury species. <4> CaH2, for organomercurials and KMnO4 for inorganic mercury. <5> Na2SO3, for all mercury species.
Output (English): 1