What can cause shifts in the aggregate demand curve?

The correct choice highlights that changes in taxes and government spending are key factors affecting aggregate demand, which is the total demand for goods and services within an economy at a given overall price level and time. When the government alters tax rates, it directly influences households' disposable income, which affects consumer spending—one of the primary components of aggregate demand. For instance, a tax cut gives consumers more money to spend, thereby increasing overall demand.

Similarly, modifications in government spending—either through increased investment in public projects or changes in public services—can significantly influence aggregate demand. Increased government spending stimulates demand by injecting funds directly into the economy, facilitating businesses, and improving consumer confidence.

The other options, while important in the broader economic context, do not primarily shift the aggregate demand curve. Changes in personal savings rates might influence short-term consumption patterns, but are not direct determinants of aggregate demand shifts. Business regulations and compliance costs primarily impact supply-side economics, affecting production costs rather than demand levels. Changes in production technologies significantly affect the aggregate supply curve by altering production efficiency and costs, rather than directly influencing aggregate demand.