A rocket moves with initial velocity v0 towards the Moon of mass M, radius r0. Find the cross section σ for striking the Moon, taking the Moon to be at rest and neglecting all other bodies. Hint: σ is the area of the cross section of the cylinder of initially parallel orbits far from the Moon that eventually strike it. The enhancement of this cross section over the pure geometrical cross section πr02 is known as gravitational focusing.

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current

Ithink the answer is d

Year  1936,  lehman predicted that the earths 'inner core' is solid. she observed that the seismic signals during her study were bent and did not pass through instead bouncing back. later it was confirmed that the earth's inner core was solid made up of nickel-iron and had a molten outer core.