with on heads?

[Cristina.ro]

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #815 "Easter Island", question 7

All of the moai have clearly ......... features with long earlobes, unhappy looking mouths, and long chins with on heads set on stunted torsos, hands meeting on the midriff.

(a) prominent
(b) personal
(c) impertinent
(d) pestilent

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #815 "Easter Island", answer 7

All of the moai have clearly prominent features with long earlobes, unhappy looking mouths, and long chins with on heads set on stunted torsos, hands meeting on the midriff.

Correct answer: (a) prominent
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Hi,

I don't understand that bit between the two brackets. Will you please explain it to me ? Why is that ''on'' there ?

All of the moai have clearly ......... features with long earlobes, unhappy looking mouths, and long chins [with on heads] set on stunted torsos, hands meeting on the midriff.

Thanks
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If you're going through hell... keep going.

[Mister Micawber]

It is a typographical error, Cristina. I have fixed it and several other problems in this test, and the changes should appear with our next database update. Thanks for pointing this out.
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Native English teacher at Mister Micawber's

[Cristina.ro]

Thank you Mr Micawber,

I kept scratching my head over this and yes, the only thing I could come up with was that it was a typo. Just wanted to make sure it wasn't some kind of grammar rule that I had not the slightest idea about. I also considered that those statues might not have been your common looking statues.

:-)
_________________
If you're going through hell... keep going.