Why is there a border between light and dark on the moon

Why is there a border between light and dark on the Moon? There is a border between light and dark on the moon because the sun illuminates the half of the moon that is facing it. Leaving the other half dark.

the federal government of the united states was established by the constitution. us is a presidential republic. the president is head of state, head of government and of a two party legislative and electoral system. the supreme court balances the powers of the federal and the state government. yhe executive branch is headed by the oresident. there are two chambers of congress, the senate and the house of representatives. judicial power is exercised by the judicial branch (or judiciary), comprised of the supreme court and lower federal courts. the judiciary's function is to interpret the   constitution as well as the federal laws and regulations.

the answer is d.index