Final answer:
The essential component for growth that can be toxic to some organisms is oxygen. Microbes demonstrate a range of oxygen requirements, with various categorizations like obligate aerobes to obligate anaerobes. Some organisms have adapted to use alternative energy sources. The correct option is 2) Oxygen
Step-by-step explanation:
The component that is an absolute requirement for growth, which may be toxic to some organisms while others can live with or without it, is oxygen.
Different types of microbes have varying requirements for oxygen. These include obligate aerobes that must have oxygen to grow, obligate anaerobes for which oxygen is toxic, facultative anaerobes that can grow with or without oxygen, aerotolerant anaerobes that do not use oxygen but can tolerate it, microaerophiles that require low levels of oxygen, and capnophiles that thrive in high carbon dioxide conditions.
While oxygen is essential for many organisms, there are those that have evolved to utilize other chemicals for energy. For instance, photosynthetic microorganisms use light energy directly.
Additionally, certain microbes can use a variety of chemicals, such as sulfur or metals, which would be toxic to many other life forms, to sustain their growth. The correct option is 2) Oxygen