Question: Felicia ta yi bincike a kan ko kalar ruwa na shafar yadda yake iya yin zafi da wuri a cikin hasken rana. Ta kwarara ruwan famfo a cikin mazubai guda biyar kuma ta zuba launin abinci cikin huɗu daga cikin mazuban biyar. Daga nan sai Felicia ta yi amfani da na'urar auna yanayin zafin jikin mutum domin auna yanayin zafin ruwan da ke cikin kowane mazubi. Wanne ne daga cikin waɗannan aka yi amfani da shi wajen gudanar da bincikenta?
Options:
cakuɗa kalolin abinci a cikin ruwa
gwada mazubin da ruwansa bai canza kala ba
amfani da yawan ruwa ɗaya a cikin duka gwaje-gwajen
gwada ruwan da ya canza launi a lokuta daban-daban 
Answer: B