One of the main transportation challenges for people living in extremely cold climates is
a.
railway tracks that constantly crack and break due to ice
b.
waterways that are frozen over half the year
c.
the high cost of travel during the winter months
d.
the inability to use anything except dogsleds in the winter months

answer is B.

Explanation:

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explanation:

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.