Fact 1: Genes that are located on the same chromosome are called linked genes.

Fact 2: Thousands of genes are linked together in a chain to form chromosomes.

Given the two facts above, answer the question "Genes that are located on the same chromosome are chained together by the what?" with the following options: 
- forces
 - light energy
 - voltage
 - thousands
 - A computer
 - sun's heat
 - photons
 - Acids


 

    thousands     