The inverter pair delay is given by

• A. (Zp.u./Zp.d.)‚Äö√†√ú‚àö√ú
• B. (1+ Zp.u./Zp.d.)‚Äö√†√ú‚àö√ú
• C. (1+ Zp.u./Zp.d.)‚Äö√†√ú‚àö√ú
• D. (1+ ‚Äö√†√ú‚àö√ú)Zp.u./Zp.d.