The expansion curve is given by the expression ___________

• A. (e_0=elog_{10} frac{ _0+ }{ _0} )
• B. (e_0=e/C_s frac{ _0+ }{ _0} )
• C. (e_0=e-C_s log_{10} frac{ _0+ }{ _0} )
• D. (e_0=e+C_s log_{10} frac{ }{ _0} )