English grammar error-spotting (sequence of tenses in reported belief/expectation): Choose the single erroneous part; select ‘‘No error’’ only if all is correct: ‘‘He was sure / that he should / win the Prize. / No error.’

Concept/Approach
After a past reporting verb of certainty/belief (‘‘was sure’’), the natural backshift for a future-in-the-past is ‘‘would’’: ‘‘that he would win …’’. ‘‘Should’’ does not express simple futurity here.

Correction
‘‘He was sure that he would win the prize.’’

Notes
Also standardize capitalization: ‘‘prize’’ is not a proper noun unless part of a title (e.g., ‘‘the Nobel Prize’’).

Final Answer
that he should