To determine which of the listed monuments is a UNESCO-acclaimed World Heritage site in Uttar Pradesh, we must examine the given options and identify which has been recognized by UNESCO.

1. Deogarh Monuments: Located in Lalitpur district, these historical Jain monuments do not have UNESCO World Heritage status.
2. Fatehpur Sikri: This is a historic city in the Agra district of Uttar Pradesh, built by Mughal Emperor Akbar. It was recognized as a UNESCO World Heritage Site in 1986. Fatehpur Sikri is noted for its stunning architecture, and as a UNESCO site, it represents cultural significance.
3. Kushinagar Ruins Stupa: Kushinagar is a major Buddhist pilgrimage center, but it is not a UNESCO World Heritage Site.
4. All Saints Cathedral: Known for its Gothic architecture, it is located in Allahabad (Prayagraj). However, it is not listed as a UNESCO World Heritage Site.

Given this analysis, the correct answer is Fatehpur Sikri, as it is the only site among the options that is recognized by UNESCO as a World Heritage Site, due to its historical and architectural significance. The other options are not listed by UNESCO as World Heritage Sites.