What does idk mean i really don’t know

Hello, i need you to me my teacher sent me a letter to the reader and in the letter i have to put in. why do i want to get 3 points? and he said that of the 4 arguments choose one and that with that argument write the letter these are the arguments: addition: also that, even that, too. comparison: more than, less than, as much as. opposition: but, however. security: without a doubt, of course. those are the 4 arguments and i have to choose just one, i need it it's very urgent you it's about language and literature

After the fall of saigon, americans a) were eager to explore the lessons of vietnam b) just wanted to forget about the war c)bought airline tickets to hanoi d)demanded that the u.s. get involved in "another vietnam"

Which practices can be used to protect our supply of freshwater?