**Answer:**

b) n = 1 to n = 4.

**Explanation:**

a ) n = 4 to n = 1 transition represents release of energy because transition is from high energy orbit to low energy orbit.

Similarly c) n = 2 to n = 1 represents release of energy because transition is from high energy to low energy orbit.

d ) n = 1 to n = 3 is also energy absorbing transition but amount of energy absorbed is less as compared with option b) transition .

So the correct option is b)

**Given Information: **

Current = I = 61 A

Magnetic field = B = 1.30x10⁻⁴

**Required Information: **

Radius of wire = r = ?

**Answer: **

r = 0.093 meters

**Step-by-step explanation: **

Biot-Savart Law is given by

B = μ₀I/2πr

Where μ₀ is the permeability of free space and it is basically a measure of resistance in the formation of magnetic field.

I is the current flowing through the wire and B is the magnitude of the magnetic field produced.

Re-arranging the above equation to find out the radius of the loop

r = μ₀I/2πB

r = 4πx10⁻⁷*61/2π*1.30x10⁻⁴

r = 0.093 m

Hence, the radius of the loop wire is 0.093 meters.