A and B are the correct answer for this
Explanation:
Given that,
2 strings both vibrate at exactly 220 Hz. The frequency of sound wave depends on the tension in the strings.
The tension in one of them is then decreased sightly, then 
will decrese.
Beat frequency, 
So, the new frequency of the string is 217 Hz. Hence, this is the required solution.
In space we feel weightlessness because the earths gravity has less effect on us.The Earths gravitational attraction at those altitudes is only about 11% less than it is at the Earths surface. If you had a ladder that could reach as high as the the shuttles orbit, your weight would be 11% less at the top.
Location & Sunlight Availability.
Solar Panels use a large amount of space.
The Sun isn't always present.
Solar Energy is Inefficient.
There is an overlooked Pollution & Environmental Impact.
Expensive Energy Storage.
High Initial Cost.
