a
\(\begin{array}{l}
\,\,\,\,\,\,Here,\bar F = \left( {3\hat i + \hat j} \right)N\\
Initial\,position,\,{{\bar r}_1} = \left( {2\hat i + \hat k} \right)m\\
Final\,position,\,{{\bar r}_2} = \left( {4\hat i + 3\hat j - \hat k} \right)m\\
Displacement,\,\bar r = {{\bar r}_2} - {{\bar r}_1}\\
\bar r = \left( {4\hat i + 3\hat j - \hat k} \right)m - \left( {2\hat i + \hat k} \right)\\
m = 2\hat i + 3\hat j - 2\hat k\,m\\
Work\,done,\,W = \bar F.\vec r = \left( {3\hat i + \hat j} \right).\left( {2\hat i + 3\hat j - 2\hat k} \right)\\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 6 + 3 = 9\,J
\end{array}\)