What natural occurrence the soviet forces?

Explanation:

the cold winter. the german soldiers were not used to the cold russian winters and the Soviet troops were. the winters in germany were milder than the winters near moscow. when hitler attacked russia he lost an ally in his fight against the allied powers. had hitler not sent his troops to attack russia and had the cold not slowed the german forces down, the nazis ccould have won the war.

when in doubt choose c

it's what my teacher told my class when we were going into psats