The country advertises of the highest number of higher education institutions in the world - an amazing 33,723, according to an EY analysis - and the second biggest number of responses in higher education at almost 27 million (to China's 33 million).

The sentence talks about a country's educational infrastructure, which is quite impressive. So, the first word can be replaced by 'boasts' and 'brags'; this eliminates options b), c) and e). With 'amazing' being correct in second place, the words 'astounding' and 'startling' can fit too, as they depict the remarkable number of institutions. Though the third word 'biggest' seems correct, it cannot be the answer as we've already eliminated option e); now, 'much' in option d) seems to provide no meaning to the sentence; this eliminates option d) too. Clearly, the answer is option a).