Mendel's work was republished in Flora by De Vries.

Explanation:

Gregor Mendel was a scientist and Augustinian friar who is known as the father of modern genetics. He conducted groundbreaking experiments on pea plants in the mid-19th century and formulated the laws of inheritance, which laid the foundation for the field of genetics.

Mendel's work on inheritance patterns was initially published in 1865 in the journal Proceedings of the Natural History Society of Brno. However, his work went largely unnoticed and was not recognized for its significance at the time.

It was later rediscovered independently by three scientists: Hugo de Vries, Carl Correns, and Erich von Tschermak. They recognized the importance of Mendel's work and sought to republish it in order to bring it to the attention of the scientific community.

De Vries, a Dutch botanist, was the first to publish a paper in 1900 that acknowledged Mendel's work and its significance. He also proposed his own theory of mutation, which he believed was a mechanism for evolutionary change. In this paper, De Vries referenced Mendel's original work and provided a detailed explanation of the laws of inheritance.

Tschermak, an Austrian botanist, also independently rediscovered Mendel's work and published a paper in the same year as De Vries. He acknowledged Mendel's contribution and discussed the importance of his experiments in establishing the laws of inheritance.

Correns, a German botanist, also independently rediscovered Mendel's work and published a paper in 1900. He conducted his own experiments to validate Mendel's findings and further contributed to the understanding of genetics.

All three scientists played a crucial role in bringing Mendel's work to the forefront of scientific research. Their independent rediscoveries and subsequent publications helped to establish the importance of Mendel's laws of inheritance and paved the way for the development of the field of genetics.

Therefore, the correct answer is option 'A' - De Vries.