A scientist noticed that in acidic pond water some salamanders developed with curved spines. This was an example of a(n) А
research
o
B
inference.
о
С
observation
D
hypothesis

С  observation

Explanation:

This mode of investigation is an example of observation.

Observations are carried out using our senses and keen inquisitiveness. It can take place within a short period of time or an extended duration.

So; noticing the change in shape of the salamanders is making an observation.

Our sight, smell, taste e.tc are all observational tools.

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation:

1: most common garden plants prefer loam — soils with a balance of different-sized mineral particles (approximately 40% sand, 40% silt, and 20% clay) with ample organic matter and pore space. however, some plants grow better in sandy soils, while others are well-adapted to clay soils.

2: available water capacity is the maximum amount of plant available water a soil can provide. it is an indicator of a soil's ability to retain water and make it sufficiently available for plant use. available water capacity is the water held in soil between its field capacity and permanent wilting point.

3: it is the same for all living things (plants and animals). it also includes very tiny organisms that our eyes cannot see. they are known as microorganisms, and include viruses, bacteria and fungi.