Final answer:
The correct answer is b) Lysosome; enzymes, reactive oxygen species, and acidic pH, as these are the factors within a lysosome which kill an ingested microbe.
Step-by-step explanation:
Once a microbe has been ingested into a phagosome, the phagosome fuses with a lysosome. Within this structure, the killing of the microbe is carried out by several factors. The three main factors involved in this process are enzymes, reactive oxygen species, and an acidic pH. The enzymes break down the microbial structures, reactive oxygen species cause oxidative damage to the microbe, and the acidic environment within the lysosome further contributes to the destruction of the pathogen. Therefore, the correct option is b) Lysosome; enzymes, reactive oxygen species, and acidic pH.