$\mathrm { A } + 5.0 - \mathrm { nC }$

Multiple Choice

$\mathrm { A } + 5.0 - \mathrm { nC }$ charge is at the point $( 0.00 \mathrm {~m} , 0.00 \mathrm {~m} )$ and a $- 2.0 - \mathrm { nC }$ charge is at $( 3.0 \mathrm {~m} , 0.00 \mathrm {~m} )$ . What work is required to bring a $1.0 - \mathrm { nC }$ charge from very far away to point $( 0.00 \mathrm {~m} , 4.0 \mathrm {~m} )$ ? $\left( k = 1 / 4 \pi \varepsilon _ { 0 } \right.$ $= 9.0 \times 10 ^ { 9 } \mathrm {~N} \cdot \mathrm { m } ^ { 2 } / \mathrm { C } ^ { 2 }$ )

A) $11 \mathrm {~nJ}$
B) $7.7 \mathrm {~nJ}$
C) $3.6 \mathrm {~nJ}$
D) $15 \mathrm {~nJ}$