According to some estimates, the united states has enough natural gas to last at current rates of use.
a.
100 years
b.
50 years
c.
10 years
d.
25 years

union blockade

explanation:

the union blockade in the american civil war was a naval strategy by the united states to prevent the confederacy from trading.

the blockade was proclaimed by president abraham lincoln in april 1861, and required the monitoring of 3,500 miles (5,600 km) of atlantic and gulf coastline, including 12 major ports, notably new orleans and mobile. those blockade runners fast enough to evade the union navy could only carry a small fraction of the supplies needed. they were operated largely by british citizens, making use of neutral ports such as havana, nassau and bermuda. the union commissioned around 500 ships, which destroyed or captured about 1,500 blockade runners over the course of the war.

the berlin blockade was an international crisis that arose from an attempt by the soviet union, in 1948–49, to force the western allied powers (the united states, the united kingdom, and france) to abandon their post-world war ii jurisdictions in west berlin. in march 1948 the allied powers decided to unite their different occupation zones of germany into a single economic unit. in protest, the soviet representative withdrew from the allied control council. coincident with the introduction of a new deutsche mark in west berlin (as throughout west germany), which the soviets regarded as a violation of agreements with the allies, the soviet occupation forces in eastern germany began a blockade of all rail, road, and water communications between berlin and the west. on june 24 the soviets announced that the four-power administration of berlin had ceased and that the allies no longer had any rights there.