Q.Choose the correct alternative and justify: A straight-line supply curve that passes through the origin shows —

Where a straight-line supply curve passes through the origin has a specific, exam-standard implication for its elasticity. …

Option (a), Perfectly elastic — incorrect. Perfectly elastic supply ($E_s=\infty$) is shown by a HORIZONTAL supply curve, not one passing through the origin.

Option (b), Perfectly inelastic — incorrect. Perfectly inelastic supply ($E_s=0$) is shown by a VERTICAL supply curve (fixed quantity regardless of price), which does not pass through the origin at a positive slope either.

Option (c), Unitary elastic — CORRECT. For a straight-line supply function of the form $Q_s = bP$ (through the origin, no constant term), price elasticity works out to $E_s = b \times P/(bP) = 1$ at EVERY point on the line, whatever the value of the slope $b$. This is a standard, testable geometric fact in the MSBSHSE Std XII Economics point-method of measuring elasticity of supply. …

Assuming a steeper line through the origin must be LESS elastic than a flatter one — slope (steepness) has no bearing on elasticity for a line through the …