Moods and Emotions

1)I'm at my ........ end. I've looked everywhere for my purse and I can't find it anywhere.

a) wits'
b) nerves'
c) senses'
2)
You look really cheesed ........ Is everything OK?

a) up
b) away
c) off
3)
I'm going to do some baby-sitting for Sarah. She sounded at the end of her ........ on the phone and I think she needs a break.

a) lead
b) tether
c) leash