What link in the chain of infection would be broken if there isn't a place for an infectious agent to thrive and reproduce?

There are six links to the chain of infection, however the reservoir is the correct link to select.

The reservoir includes all the places in the environment where the pathogen or infection lives (this includes people,  animals and insects, medical equipment, and soil and water)

both male and female gametes are produced by meiosis of the germ cells. therefore, both male and female gametes are haploid. one male and one female gamete unite during the fertilization to form the diploid zygote. in seed bearing plants, pollen grain is the male gametophyte, which produces sperm cells.

examples of nucleic acids are deoxyribonucleic acid (dna) and ribonucleic acid (rna).