Hi Veena,
The Sun site will tell you what is on the exam, but quoting from it:
Section 7 (second bullet) 'Recognize conditions that might prevent a thread from executing.'
Section 9 (first bullet) 'Make appropriate selection of collection classes/interfaces to suit specified behavior requirements'
From this it sounds like
you should do both! If it's any help, I didn't cover interrupt(), but did do Iterator and ListIterator in Collections, and I passed. Other people may have different ideas though.
Good Luck,
Helen