What do scientists hope to accomplish using recombinant DNA?

Ability to prevent infectious disease

Replacement of defective genes with normal genes

Easy access to medical treatment for individuals with any genetic disease

Cheaper medications for those with single-gene diseases

The correct answer is: Replacement of defective genes with normal genes

Recombinant DNA molecules are made in laboratory by the methods of genetic recombination such as molecular cloning. The aim of these methods is to bring together genetic material from different sources, creating "combinations" that usually couldn't be found in the genome. The process of recombination is possible because, DNA molecules from all organisms share the same chemical structure (nucleotides are same among different species, difference is only in the nucleotide sequence).