Yeast haploid cells secrete pheromones to other yeast to indicate they want to mate, and others respond by growing toward these potential mates. The pheromones bind to a receptor, which eventually leads to increased expression of transcription factors required for this growth. This best exemplifies which of the following?

(A) Chemical inhibition due to the intracellular binding site

(B) Passive transport since the haploid cells require less energy

(C) Mitotic division due to anaphase elongation (D) Signal transduction affecting cell function