That: at, som eller det?

The English word that has three different functions, which are expressed by three different words in Danish:

1) That may initiate a phrase expressing the object of verbs like to say, to reply, to think, to dream, to shout etc. :

He said, that he keeps his umbilical cord in a jar in the freezer.

(Han sagde, at han har sin navlesteng i fryseren)

At may be left out if doing so won't disturb the meaning.

2) That may initiate a relative clause that describes or defines an element of the main clause:

The jar that he keeps in his freezer gives me the creeps

Glasset, som han har i sin fryser, giver mig myrekryb.

Som may be left out if is not the object of the phrase.

3) That may serve as demonstrative pronoun, pointing out or referring:

What would happen if that jar fell into the hands of a mad genetic engineer? That could be dangerous!

Hvad ville der ske, hvis det glas faldt i hænderne på en gal gensplejser? Det kunne blive farligt !

Choose at, som eller den/det in the drop down list. Choose (-) if the word may be left out. (counts as alternative answar).