A vector \[\vec{a}\] is turned without a change in its length through a small angle \[d\theta \]. The value of \[|\Delta \vec{a}|\] and \[\Delta a\] are respectively

• A. \[0,\,a\,d\theta \]
• B. \[a,\,d\theta ,\,\,0\]
• C. 0, 0
• D. None of these