Answer:
research question: how do different humidity levels affect the heights of different types of trees
independent variable: humidity level
dependent variable: tree height
constants: temperature, light, duration of time
control group: tree left outside in normal conditions
Explanation:
A parasite moving between individuals other than parents and their offspring uses
horizontal transmission.
Horizontal transmission is the transmission of infections between (parasites) that are not in a parent-child relationship (vertical transmission). Horizontal transmission may include the carriers or <span>vectors which are other species. Transmission, in that case, occurs via the bite of the vector (an infected organism), like in malaria.</span>