Logical sequence in penicillin production process Steps:

• Start with nutrient addition to support fungal growth (stage 1).
• Filter the initial mixture to remove impurities and prepare the medium (stage 3).
• Allow the fungus to secrete penicillin during fermentation (stage 4).
• Note that extraction (stage 2) follows later, but the query focuses on the preparatory sequence.

Why A is correct:

• Stage 1 provides essential nutrients like corn steep liquor and yeast extract, followed by filtration (3) for sterility, enabling secretion (4), aligning with fermentation protocols.

Why the others are wrong:

• B: Extraction (2) cannot precede nutrient addition or secretion.
• C: Filtration (3) requires prior nutrient addition (1).
• D: Secretion (4) needs nutrients first, not after filtration and addition.

Final answer: A