a.Now think about the global oil market. In 2019, average monthly crude oil prices were relatively stable, always between $50 and $65 per barrel. But as COVID-19 hit in the first few months of 2020, oil prices declined sharply, reaching an average price of less than $20/barrel in April. Using Supply-Demand (S-D) analysis, which of the curves (S, D, or both) likely shifted in those first months of 2020, and in which direction(s)? What could explain the shift(s)? [1 line]

Chart 2. 12-month percent change in CPI for All Urban Consumers (CPI-U), not seasonally adjusted, Jan. 2020 - Jan. 2021 Percent change 2.5 2.0 1.5 * X * 1.0 0.5 0.0 Jan'20 Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan'21 X X X All items All items less food and energy