Which of the following is true?
◦ GWAS can scan the entire genome for QTLs by statistically testing for marker variants.
◦ QTL mapping approaches can analyze organisms in random mating populations.
◦ GWAS requires controlled crosses and the formation of introgression lines.
◦ QTL mapping can directly identify the gene responsible for the associated phenotypic variation.
◦ GWAS is able to determine a single gene that plays the sole role in the development of Crohn's disease.