world history....few questions help asap!?

[Dior]

History has never been a good subject for me. can someone please point me in the right direction to the correct answer please. thank you so much!

The failure of the Schlieffen Plan was finally made apparent by
A United States entrance into the war.
B continued British control of the seas.
C Russian defeat in Tannenberg.
D German defeat at the Battle of the Marne.

Russia felt compelled to aid Serbia in order to maintain
A its position as defender of Slavic interests.
B its membership in the Triple Entente.
C its relationship with France.
D the principle of Serbian neutrality.

As the war settled into a stalemate, countries tried to maintain citizens' morale by
A agreeing to halt the use of dreaded poison gas weapons.
B keeping civilians out of the war effort.
C focusing factory production on consumer goods.
D spreading propaganda.

Great Britain put aside its reluctance and entered the war when Germany
A marched into Luxembourg.
B issued its ultimatum to Russia.
C declared war on France.
D refused to withdraw from Belgium.

The prime minister of Russia's provisional government and a leader in the Petrograd Soviet was
A Kerensky.
B Rasputin.
C Lenin.
D Trotsky.

[Hurin-of-Emyn-Arnen]

D German defeat at the Battle of the Marne.

A its position as defender of Slavic interests.

D spreading propaganda.

D refused to withdraw from Belgium.

A Kerensky.