In Isotropic radiation, which of the following vector component is absent in pointing vector?

• A. \(\widehat{a_r}\)
• B. \(\widehat{a_\theta}\)
• C. \(\widehat{a_\emptyset}\)
• D. Both \(\widehat{a_\theta} \,and\, \widehat{a_\emptyset} \)