A government seeking to reduce the level of aggregate demand through fiscal policy will most likely increase:

Increasing personal income tax rates is an effective tool for a government aiming to reduce aggregate demand through fiscal policy. When personal income taxes rise, individuals have less disposable income available to spend. This decrease in consumer spending leads to a reduction in overall demand for goods and services within the economy. As households cut back on their consumption due to higher taxes, businesses also experience lower sales, which can further dampen economic activity.

In contrast, increasing interest rates is more related to monetary policy rather than fiscal policy. Spending on infrastructure typically aims to stimulate the economy and would not aid in reducing aggregate demand. Similarly, raising corporate tax rates could impact business investment, but it may not have an immediate or direct effect on consumer spending, which is a critical component of aggregate demand. Thus, increasing personal income tax rates is the most coherent and direct approach for achieving the goal of reducing aggregate demand through fiscal policy.