Final answer:
Nonpathogenic bacteria that decompose dead matter are known as decomposers. They play a vital role in ecosystems by recycling nutrients through the breakdown of dead materials and waste products.
Step-by-step explanation:
Nonpathogenic bacteria that live on dead matter are known as decomposers. These organisms play a critical role in ecosystems by breaking down dead materials and waste products, thereby recycling nutrients such as nitrogen back into the environment. Decomposers like bacteria and fungi are essential for the cycling of nutrients, without which ecosystems would not function properly.
There are several types of decomposers, including detritivores and saprotrophs. The latter specifically feed on the remaining organic matter after other decomposers have done their work, breaking down complex organic substances into simpler inorganic substances, which can then be taken up by producers to synthesize new organic compounds.
Therefore, the correct answer to the question is option 1) Decomposers. These nonpathogenic bacteria that decompose dead organic material play an indispensable role in maintaining the balance of ecosystems.