Trailing only South Korea, Australia and Singapore

Taiwan has the fourth highest dining-out costs in the Asia-Pacific region, trailing only South Korea, Australia and Singapore.

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Which one does 'trailing only South Korea, Australia and Singapore' modify?

a. the fourth highest dining-out costs
b. Taiwan
c. Taiwan has the fourth highest dining-out costs in the Asia-Pacific region

Would you be so kind as to help me? Thanks!

PS I also posted the same question on https://goo.gl/X9xJp4, but all of your answers are unique to me. Hope we can discuss with each other. Thank you.