Answer:
Chemicals that are secreted from antigen-presenting cells then activate helper T cells.
Explanation:
The correct answer for this question is "shaded square." The symbol that would the horse breeder use to show a male who is affected by a defective gene is the shaded square. <span>Pedigree charts use shaded symbols to show organisms that have a particular trait, such as a defective gene, being traced in the chart. </span>
Anything that doesn't have to to with the living organisms or life in that sphere such as a rock or the dirt. It would help if you posted options. :) hope this helped