( A ) $\overrightarrow{\tau} = \overrightarrow{p}+\overrightarrow{E}$
( B ) $\overrightarrow{\tau} = \overrightarrow{p}.\overrightarrow{E}$
( C ) $\overrightarrow{\tau} = \overrightarrow{p}-\overrightarrow{E}$
( D ) $\overrightarrow{\tau} = \overrightarrow{p} \times \overrightarrow{E}$