Which of the following best exemplifies secondary endosymbiosis [en-doh-sim-bee-OH-sis]?

W) Human white blood cell phagocytosis [tag-uh-sy-TOH-sis] of a pathogenic bacterium X) Cyanobacterium [sy-uh-noh-bak-TEER-ee-uhm] is engulfed by a heterotrophic eukaryote [het-er-uh-TROF-ik yoo-KAR-ee-onf]

Y) A heterotrophic eukaryote engulfs a green algal eukaryote Z) Receptor mediated endocytosis [en-doh-sy-TOH-sis]
Y) HETEROTROPHIC EUKARYOTE ENGULFS A GREEN ALGAL EUKARYOTE