Barron's TOEFL model test:

Some 40 million people today receive their electricity from geothermal energy at a cost competitive with that of alternative energy sources.

The word alternative in the passage is closest in meaning to

  1. numerous
  2. optional
  3. nearby
  4. equivalent

The answer was "optional". Barron's explanation:

In this passage, optional is a synonym for “alternative.” Context comes from the contrast of “geothermal energy” and “other” energy sources.

But the sentence makes no sense to me after substituting "optional" for "alternative". Could anyone explain?

  • Makes little sense to me either. Without a word list I'd have gone for 'other', or perhaps 'mainstream'. BTW 'alternative' in this strict sense referring to electricity supply already means 'other than the main sources', coal, hydroelectric, nuclear etc. [Compare to 'alternative medicine', which is that which has either not been proven to work, or proven not to work. Once alternative medicine is proven to work, it's called … medicine. ;) Sep 17, 2022 at 11:14

1 Answer 1


I agree that 'optional' is not a synonym for 'alternative' in this case.

Optional would mean an energy source you didn't have to use at all. That's... not a realistic option for most energy consumers.

"Alternative" could mean a different selection from the available choices. It often has the additional meaning of 'not mainstream'. For instance, geothermal could be considered 'alternative' meaning as opposed to traditional energy sources like fossil fuels.

I would prefer equivalent as the closest in meaning to alternative. Meaning that it was equivalent in satisfying the needs of the people who are energy consumers.

It may be that the person writing the question thought 'optional' means 'an option'. 'An option' is the same as 'an alternative'. But 'optional' is not the same thing as 'an option'. And 'alternative' isn't the same thing as 'an alternative'.

But that's just speculation.

You can congratulate yourself on a superior understanding of English to the test writer. However, I can only wish you luck convincing Barron's, as test creators tend not to respond well to suggestions that their questions are wrong.

  • Thanks! I felt that there were many wierd answers in Barron's practice tests, so I came here to see if it's just me. And apparently not :)
    – John
    Sep 19, 2022 at 22:33

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