Answer:
B/4
Explanation:
The magnetic field strength is inversely proportional to the square of the distance from the current. At double the distance, the strength will be 1/2^2 = 1/4 of that at the original distance:
The field at twice the distance is B/4.
The correct answer is "3. Both increase"
In fact, the frequency of a vibrating string is given by

where L is the length of hte string, T the tension and

the linear mass density.
We can see that string is made shorter, L decreases, so the frequency f increases. And since the pitch has the same behaviour of the frequency, it increases as well.
105 J because work done is force times distance
Don't worry eventually it is going to stop somewhere or land right