A proton is fired directly toward a fixed point charge of +2μC that is located in free space. If the proton starts from rest at a very great distance, the minimum initial speed it must have so as to reach a point 0.50m from the charge is closest to
a) 8.3×106ms−1
b) 2.6×106ms−1
c) 3.7×106ms−1
d) 8.3×105ms−1