The correct answer is A) the Soviets felt it took too long for the allies to invade France.
A cause of Soviet mistrust of the Western Allies in World War II was that the Soviets felt it took too long for the allies to invade France.
The mistrust also had other reasons. Relationships between the United States and Russia were not good since 1917, due to the Communist activities in Russia. Differences continued in the coming decades until the circumstances forced Russia to allied with Britain, France, and the United States. In 1942, Joseph Stalin wanted to open a second war front in the Soviet territory but the Allies did not accept the idea. Then, Stalin did not like the decision of invading France so late.
It was triggered when the allies had to invade France, it took them more time than what the Soviets believed necessary, so with that they started to lose trust in the allies.
