Why does London put barriers on the rails?

for protection and awareness

Explanation:

Hampstead

The deepest station is Hampstead on the Northern line, which runs down to 58.5 metres. 15. In Central London the deepest station below street level is also the Northern line. It is the DLR concourse at Bank, which is 41.4 metres below.

the answer is d. tariffs were raised by america's trading partners after the smoot-hawley tariff act, decreasing exports, and declining job rates.

hello there the answer is a

sorry if i am wrong hope that : )