The correct answers are We just ran out of milk, so please buy some at the store! and Can you pick up the birthday cake from the bakery at noon?

"Run out of" means to use all of your supply of something so that there is none left.

"Pick up" means to collect something or someone from a place.

"Look after" means to take care of someone/something. If you lost your keys, you need to "look for" (search for) them!

"Drop off" means to deliver someone or something to a destination, but you would "hang up" balloons on the ceiling.