This instrument, which uses the earth’s magnetic field to indicate direction, revolutionized travel. what instrument, invented during the tang dynasty, is described above?
a. compass
c. celadon
b. movable type
d. gunpowder

a. compass

Explanation:

    The compass is an object used for geographical orientation. Its construction took place with reference to the wind rose, which is composed of cardinal, collateral and subcolateral points. It is an object with a magnetic needle that is attracted to the earth's magnetic pole.

    The development of the compass dates from the year 2000 BC, and the search for its improvement took place for centuries. Considerable progress was made when it was discovered that a thin piece of metal could be magnetized by rubbing it with iron ore. In 850 AD, the Chinese, in search of greater precision of this instrument, began to magnetize needles in order to gain greater precision and stability, then came the compass - which currently works on the same principle developed by the Chinese.

they were destroyed coming out of the civil war but after he war they were booming. if you need an in-depth answer follow up with me  

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