Final answer:
Policymakers may have estimates of the spending multiplier and potential output but are subject to uncertainty; fiscal policy has some flexibility but is bound by economic and political factors.
Step-by-step explanation:
Out of the statements provided about fiscal policy and its effects, the statement that policymakers know the values of key macroeconomic variables like the spending multiplier is not accurate. Although policymakers have an idea about the spending multiplier, it can fluctuate based on various economic conditions, making it difficult to know the exact values.
Additional ,fiscalpoliciess interventions can conflict with other government goals, and while policymakers may have an estimate of potential output, it is subject to uncertainty and revisions. Finally, government tax and spending policies offer a degree of flexibility, though not without constraint,s and are often the subject of political debate and economic conditions. Therefore, the true statement in the context provided would be that tax and spending policies can be flexible to some extent but are impacted by complex economic and political factors.