Which of these is not a defense mechanism for the Berlin Wall Guard Tower Barbed Wire All of these were used Land Mines Brushed Sand Pit

All of these were used.

Explanation:

During the cold war, between 1961 to 1989, many people from East Germany sought to move over to the more accommodating West Germany. More than two million people were successful in their attempt at moving over. To prevent further exit, the Berlin Wall was built.

The wall was safeguarded with barbed wires, three thousand dogs, land mines, guard towers, car trenches, or sandpits/ditches to sink any car moving across. Despite all these measures put in place, some people still attempted to move through the hurdles. Some of them lost their lives in the process.

the answer is a) high entry costs

the constitution gives congress the power to regulate commerce "among" the several states.