The change in quantity supplied of red wine is a result of a change in market price. Moving from point A to B or C is a movement along the supply curve. The actual supply curve did not change shape, only the market price for red wine changed and thus the quantity supplied by the producers changed.
The dream of spanning the Golden Gate Strait had been around for well over a century before the Golden Gate Bridge opened to traffic on May 28, 1937. Pedestrian Day was held on May 27, 1937. We do not have the exact employment figures. The Bridge was built by 10 different prime contractors and their subcontractors.
February 1933: Work began on the east approach road from San Francisco that extended through the Presidio to the south end of the Golden Gate Bridge.