Explanation

When the quantity of a good or factor supplied is completely fixed in amount regardless of price, the price elasticity of supply is zero - supply is perfectly inelastic. On a standard diagram with price on the vertical axis and quantity on the horizontal axis, a constant quantity at every price is represented by a vertical line. A horizontal curve would represent perfectly elastic supply, and an upward-sloping curve represents the normal positive relation between price and quantity supplied. Hence option C is correct.