Which is a shared power in the federal system?

In a federal system, shared powers refer to those authorities and responsibilities that are exercised by both the national and state governments. Collecting taxes is a prime example of this, as both levels of government have the power to levy and collect taxes from individuals and businesses. This ability allows both the federal and state governments to generate necessary revenue to fund their respective programs and services.

The other options represent powers that are not shared in the same way. For instance, declaring war is a power exclusively reserved for the federal government, as it involves national defense and foreign policy decisions. Similarly, establishing post offices is a power that belongs solely to the federal government, as it is related to national communications and transportation networks. Making treaties is also a power that resides exclusively with the federal government, as it pertains to international relations and requires a cohesive national strategy. Thus, collecting taxes stands out as a shared power within the framework of federalism.