A) movement of transposable elements
B) exon shuffling
C) gene duplication
D) crossing-over between homologous chromosomes

A) genes that do not sort independently due to their being physically near each other on the same chromosome
B) genes that affect two different traits and that lead to a 9:3:3:1 phenotype ratio in a dihybrid cross
C) different alleles of the same gene
D) genes whose effects combine to affect a single characteristic

A) loss of muscular strength in the arms
B) loss of reproductive ability
C) loss of central vision
D) loss of neural control in the legs