Any of the above examples would be feasible on the basis of the clue above, however if it is a crossword question and they have given some more information to the clue then you may be able to reduce these options down. Here are some helpful tips for completing crosswords and working out the possible words which make up the puzzle:
Start by looking through all of the questions and fill in the ones you definitely know the answers to first (this will fill in some of the letters of the more difficult answers).
Have a thesaurus handy so that you can check for answers such as the one above where all it basically wants is another for a given word.
If you have a computer to hand, there are actually online crossword cheat websites where you can put in the question and it will search for possible answers.
Similar to the above method, you can also buy small electronic devices which carry out the same function, but much are more conveniently (especially when traveling).
Keep going back to the difficult questions as you complete more of the crossword as it may become obvious quite quickly.
If you really cannot work out the answer, try and think outside of the box. The question may not be as literal as you are expecting; instead it may be a suggestive clue (these can be the most difficult).
Reread clues to see if there are any hidden clues within them, for example are they asking for a plural answer etc.
Finally the best advice is to use a pencil rather than a pen to fill in the answers. No matter how convinced you are of an answer just remember there may well be hundreds of possible words which fit in the space given and are perfectly feasible answers to the clue; however they may not work with the letters for other answers.