<span>the answer is :
permanent magnets
</span>A permanent magnet<span> is an object made from a material that is </span>magnetized<span> and creates its own persistent magnetic field. An everyday example is a </span>refrigerator magnet<span> used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called </span>ferromagnetic<span> (or </span>ferrimagnetic<span>). These include </span>iron<span>, </span>nickel<span>, </span>cobalt<span>, some alloys of </span>rare-earth metals<span>, and some naturally occurring minerals such as </span>lodestone<span>. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of </span>magnetism<span>.</span>
DNA is a structure that can be compared to A) Blueprints. This is because of DNA's role in the cell. DNA tells ribosomes how to make proteins just like a blueprint tells workers how to build a building.
<span>The delineation of an aquatic ecosystem is the process of spatial identification, mapping and recording of the site; description documents the critical components and processes that underpin the ecosystem values of the site, and develops conceptual model(s) and identifies threats.
Delineating an aquatic ecosystem often starts with defining the main aquatic elements (core elements). The core elements will often be distinct landforms or features such as a waterhole, a swamp, a lake or a river. Ecotonal areas may be included as part of the core element or may be considered as a separate zone. For example, riparian vegetation is often considered to be an integral part of a river ecosystem, even if only inundated in big flood events.
The area around the core elements that has a critical influence on ecosystem function is referred to here as the Ecological Focal Zone. Beyond this, the landscape may be usefully differentiated as a Zone of Influence and a Catchment Zone.</span>
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I think it is 3, 1, and 6, please tell me if I am wrong, thanks