Question

a fall in production costs will result in supple and a shift of the supply curve

Answer 1

Changes in production cost and related factors can cause an entire supply curve to shift right or left. This causes a higher or lower quantity to be supplied at a given price.

A supply curve demonstrates how the delivered amount will alter as prices rise and fall, assuming ceteris paribus— no other economically appropriate factors change. If other supply-related factors change, the entire supply curve will alter. A supply shift implies a change in the delivered amount at any cost.
Say, for a certain type of vehicle, we have an original supply curve. Now imagine that the cost of steel— an significant ingredient in the production of cars — is rising so that it becomes more costly to produce a vehicle. This cost increase will result in the supply curve shifting to the left