Time taken by the sunlight to pass through a window of thickness 4 mm whose refractive index is 1.5 is [CBSE PMT 1993]

• A. \[2\times {{10}^{-8}}\] sec
• B. \[2\times {{10}^{8}}\] sec
• C. \[2\times {{10}^{-11}}\] sec
• D. \[2\times {{10}^{11}}\] sec