How does the graph of g(x)=2⌈x⌉ differ from the graph of f(x)=⌈x⌉? a. multiplying by 2 compresses the graph of g(x)=2⌈x⌉ vertically by a factor of 2. b. multiplying by 2 stretches the graph of g(x)=2⌈x⌉ vertically by a factor of 2. c. multiplying by 2 shifts the graph of g(x)=2⌈x⌉ up 2 units. d. multiplying by 2 shifts the graph of g(x)=2⌈x⌉ down 2 units.