Sam is preparing her boyfriend's favorite chili, and as specified in the recipe she has used 18 grams of salt. When her boyfriend tastes the chili, he tells Sam that she needs to add more salt. According to "Weber's Law" what is the minimum amount of salt that Sam needs to add for her boyfriend to notice that she has added more salt? (Note: The last time that Sam made the chili, her boyfriend was able to just notice a difference in the saltiness of the chili when she increased the salt in the recipe from 9 grams to 12 grams). A) 6 grams B) 1 gram C) 9 grams D) 20 grams E) 36 grams
