A commensal bacterium 1. may also be an opportunistic pathogen. 2. always causes disease in its host.3. isn't capable of causing disease in its host. 4. is beneficial to its host. 5. does not receive any benefit from its host.

Beneficial to its host.

Explanation:

Commensalism is a relationship when a bacterium lived in the host body, get food from the host and in return provide essential nutrients to the host. It is the beneficiary relationship.

For example, many bacteria lived in the human gut act as normal flora of the gut. These bacteria or normal flora get food from the gut and in return provide them essential vitamins and nutrients.

i'm gonna put a couple so you can chose from

explanation:

if you know the fur color of the offspring mice, you can use the ratios to identify the genotypes of the parents.

if either parent mouse passes a dominant allele, the offspring will have black fur.

if the parental mice has two different fur color (i.e white and black) , the color of the offspring's fur would be either black, white, or the combination of both (grey)

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1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint