a) C.R.=\(\frac{Total \, cylinder \, volume}{Clearance \, Volume} \)
b) C.R.=\(\frac{Clearance \, Volume}{Total \, Clearance \, Volume} \)
c) C.R.=\(\frac{Total \, clearance \, volume}{Cylinder \, Volume} \)
d) C.R.=\(\frac{Clearance \, volume}{Total \, cylinder \, volume} \)

Answer: a
Explanation: Compression ratio is the ratio of the volume of the charge at the beginning of the compression stroke to that at the end of the compression stroke, i.e., ratio of total cylinder to clearance volume or \(\frac{Swept \, volume+Clearance \, volume}{Clearance \, Volume}.\)