Nicotiana sylvestris flowers only during long days and N.tobacum flowers only during short days. If raised in the laboratory under different photoperiods. they can be induced to flower at the same time and can be cross fenjlized to produce self-fertile offspring. What is the best reason for considering N. sylvestfis and N. tobocum to be separate species?

Options

A. They are physiologically distinct
B. They are morphologically distinct
C. They cannot interbreed in nature
D. They are reproductively distinct