Q)
The vector \( 2\hat i + \propto\hat j + \hat k \) is perpendicular to the vector \( 2\hat i - \hat j - \hat k \) if \[ \begin{array} (A) \: \propto = 5 \quad & (B) \: \propto = -5 \\ (C) \: \propto = -3 \quad & (D) \: \propto = 3 \end{array} \]
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