In his classic experiments on pea plants, Mendel did not use:

Correct option is C. Pod length
Mendel used seven pea plant traits in his hybridization experiments, which include flower colour (purple or white), flower position (axil or terminal), stem length (long or short), seed shape (round or wrinkled), seed colour (yellow or green), pod shape (inflated or constricted), and pod colour (yellow or green). Pod length is not included.