Soviet armies fighting germany benefited from
a. polish aid
b. cold weather
c. access to the mediterranean for supplies
d. chinese aid

Cold weather is the best answer!

a) - Poland was also at war with the Soviet, unlikely it would help
b) Soviet Union has only very limited access to the Mediterranean, which likely was completly cut off at the time anyway
c) they could have it, but China was too busy fighting its own war!

Both countries had to aprove annexation.