The contact pressure PC, tyre pressure P, and rigidity factor R are related by

• A. \(\frac{{\rm{P}}}{{{{\rm{P}}_{\rm{C}}}}} = {\rm{R}}\)
• B. \(\frac{{{{\rm{P}}_{\rm{C}}}}}{{\rm{P}}} = {\rm{R}}\)
• C. P × PC = R
• D. \({\rm{R}} = {\rm{\;}}\sqrt {\left( {{\rm{P}} \times {{\rm{P}}_{\rm{C}}}} \right)} \)