Short Run vs. Long Run in Production

Steps:

• Define short run: period where at least one input (factor) is fixed, limiting adjustments.
• Define long run: period where all inputs are variable, allowing full scale changes.
• Compare definitions to choices: seek exact match for fixed in short run and variable in long run.
• Select B as it precisely states fixed factor in short run and all varied in long run.

Why B is correct:

• Matches standard economic definition: short run fixes at least one factor (e.g., capital); long run varies all factors for optimal adjustment.

Why the others are wrong:

• A: "Can be varied" implies possibility but not the defining variability of long run.
• C: Reverses both; short run fixes factors, long run varies them.
• D: Inverts concepts; short run varies most but fixes one, long run varies all.

Final answer: B