Final answer:
The most direct evidence that DNA is the genetic material comes from DNA sequencing, which allows for reading the genetic sequences and identifying the information encoded in the DNA.
Step-by-step explanation:
The strongest direct evidence that DNA is the genetic material comes from DNA sequencing methods. DNA sequencing involves cutting the DNA into fragments, using the chain termination method, staining the DNA with fluorescent dyes, and then analyzing the entire DNA fragment with a computer. This comprehensive approach allows researchers to read the sequences of DNA and thereby determine the genetic information it contains. While other methodologies such as PCR, X-ray crystallography, and gel electrophoresis play crucial roles in DNA analysis, DNA sequencing provides the most direct evidence of DNA's role as the carrier of genetic information.