Which of the following pair of plants has a nuclear type of...

Based on the mode of development, endosperm is of three types: nuclear, cellular, and helobial.

In the nuclear type of endosperm, the primary endosperm nucleus undergoes repeated free nuclear divisions without cell wall formation. Examples include Wheat, Sunflower, Maize, Cotton, and Capsella.

In the cellular type of endosperm, every division of the primary endosperm nucleus is followed by cytokinesis. Examples include Petunia, Balsam, and Datura.

In the helobial type of endosperm, the first division is followed by cytokinesis forming two unequal cells, and subsequent divisions are free nuclear. Examples include Asphodelus and Eremurus.

Therefore, Wheat and Sunflower represent the pair of plants having a nuclear type of endosperm.

Answer: Wheat and Sunflower