An object is displaced from point $A(2m,3m,4m)$ to a point B $(1m, 2m, 3m)$ under a constant force. $\hat F=(2 \hat i+3 \hat j+4 \hat k)$. Find the work done by the force

Question

$$(a)\;-9\;J \quad (b)\;6 \;J \quad (c)\; 9 \;J \quad (d)\;-6\;J$$