To solve this problem, we need to identify which organism is correctly matched with the product it produces. Let's analyze each option:$\newline \bullet$Option 1: Methanobacterium: Lactic acid$\newline$ - Methanobacterium is a genus of archaea that produces methane, not lactic acid.$\newline$ - Therefore, this option is incorrect.$\newline \bullet$Option 2: Penicillium notatum: Acetic acid$\newline$ - Penicillium notatum is known for producing the antibiotic penicillin, not acetic acid.$\newline$ - Therefore, this option is incorrect.$\newline \bullet$Option 3: Saccharomyces cerevisiae: Ethanol$\newline$ - Saccharomyces cerevisiae, commonly known as brewer's yeast, is used in the fermentation process to produce ethanol.$\newline$ - Therefore, this option is correct.$\newline \bullet$Option 4: Acetobacter aceti: Antibiotics$\newline$ - Acetobacter aceti is a bacterium used in the production of acetic acid (vinegar), not antibiotics.$\newline$ - Therefore, this option is incorrect.$\newline$Based on the analysis, the correct match is:$\newline$Option 3: Saccharomyces cerevisiae: Ethanol$\newline$Thus, the correct option is Option 3.