Which of the following is an example of how microbes can be beneficially used by humans?

• A. Production of antibiotics such as penicillin
• B. Causing infectious diseases like tuberculosis
• C. Erosion of metal structures
• D. Formation of acid rain

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the question is asking for an example of a beneficial use of microbes by humans, meaning how microbes help or provide advantages rather than cause harm.
2. Step 2: Review each option and classify it as beneficial or harmful. For example, 'Production of antibiotics such as penicillin' involves microbes producing substances that help treat infections, which is beneficial.
3. Step 3: Recognize that 'Causing infectious diseases like tuberculosis' is harmful because it involves microbes causing illness.
4. Step 4: Note that 'Erosion of metal structures' and 'Formation of acid rain' are environmental damages caused by microbial activity or related processes, so these are harmful effects.
5. Step 5: Conclude that the beneficial example is the production of antibiotics, where microbes are used by humans to create medicines that fight bacterial infections.