Which was not a key achievement of the Ming Dynasty?

the rebuilding of the Great Wall

At that time, the Chinese citizens had to face constant threats from the barbarian that resided on the northern part of their territory.The previously built wall was not strong enough and able to be destroyed by the invaders. Ming Dynasty took the credit of rebuilding and strengthening the structure of the great wall.

254.34

step-by-step explanation:

the formula for area of a circle is given by

a = pi * r^2

a = pi * 9^2

a = 81*pi

using 3.14 as an approximation for pi

a = 3.14*81

a = 254.34

what are you options