Which of the following species has the chromosome complement similar to that of Triticum aestivum?

The correct option is Gossypium. The chromosome complement of Triticum aestivum (2n=26) is similar to that of Gossypium whose ploidy level is also 2n=26. Zea mays has a ploidy level of 2n=20. Secale and Aegilops both have the similar ploidy level of 2n=14.