In the Plant Genus Triticum There Are Many Different Polyploid

In the plant genus Triticum there are many different polyploid species,as well as diploid species.Crosses were made between three different species,and hybrids were obtained.The meiotic pairing was observed in each hybrid and is recorded in the following table.(A bivalent is two homologous chromosomes paired at meiosis,and a univalent is an unpaired chromosome at meiosis.) $\begin{array}{ll}\text { Species crossed to make hybrid } & \text { Pairing in hybrid } \\\text { 1. T. turdigum } \times \text { T. monococcum } & 7 \text { bivalents }+7 \text { univalents } \\\text { 2. T. aestivum } \times \text { T. monococcum } & 7 \text { bivalents }+14 \text { univalents } \\\text { 3. T. aestivum } \times \text { T. turdigum } & 14 \text { bivalents }+7 \text { univalents }\end{array}$

The first cross suggests a diploid and tetraploid individual were involved with one set of 7 chromosomes in common.Based on the other crosses,which species is the likely diploid individual?

A) T.turdigum
B) T.monococcum
C) T.aestivum
D) T.turdigum or T.monococcum