P6.8 Assume that we are using cartesian coordinates in the flat spacetime of special relativity. Which one of the following equations might possibly express the cor-rect tensor generalization of Newton’s second law for a particle with mass m and charge q moving in an elec-tromagnetic field Fno with four-velocity un ? Also explain why each of the other proposed equations is not credible. (Hints: Focus more on form than on content. Note that t is the coordinate time measured in our inertial frame, where x is the proper time measured by the particle itself along its worldline.) A. m dt du C. m d du E. m dt du n = qFno n t = qFnouo n = qF u no o B. m d du D. m d d u F. m d du x qF= n x = n n x qF u