(a) Time interval during which an electron moves through the region between the plates is : (A) $9.0 \times 10^{-9} \text{ s}$ (B) $1.67 \times 10^{-8} \text{ s}$ (C) $1.67 \times 10^{-9} \text{ s}$ (D) $2.17 \times 10^{-9} \text{ s}$ OR (b) The vertical displacement of the electron which travels through the region between the plates is : (A) $10 \text{ mm}$ (B) $4.9 \text{ mm}$ (C) $5.9 \text{ mm}$ (D) $3.0 \text{ mm}$