The DNA Double Helix concept was given by

Correct option is A

The double helix structure of DNA was proposed by James Watson and Francis Crick in the year 1953. Their model explained base pairing, replication mechanism, and genetic information storage. Thus, the DNA double helix concept was given by Watson and Crick.
Information booster: The Watson and Crick model is based on X-ray diffraction data produced by Rosalind Franklin. DNA consists of two antiparallel strands held together by hydrogen bonds between complementary bases. The double helix structure explains semi-conservative replication of genetic material. This discovery laid the foundation for modern molecular biology and genetics.
Why other options are incorrect: (b) Mendel worked on inheritance laws, not DNA structure. (c) Griffith discovered bacterial transformation, not the DNA model. (d) Hershey and Chase proved DNA as genetic material but did not propose its structure.