Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Class | Type | Ships | Displacement | Note |
| --- | --- | --- | --- | --- |
| Rari class | Tug supply vessel | A635 Revi | 1,450 tonnes |  |
| Malabar class | Ocean going tug | A664 Malabar\nA669 Tenace | 1,440 tonnes | Ice-breaking capabilities to 2 meters level ice |
| UT507 class | Salvage Tug | Abeille Flandre\nAbeille Languedoc | 1,500 tonnes | Chartered |
| UT515 class | Salvage Tug | Abeille Bourbon\nAbeille Liberté | 4,000 tonnes | Chartered |
| UT710 class | Support, Assistance, Pollution control vessel | Argonaute\nJason | 2,100 tonnes | Chartered, configured to accommodate NATO Submarine Rescue System |
| UT711 class | Support, Assistance, Pollution control vessel | Alcyon\nAilette | 2,000 tonnes | Chartered |
|  | Training ships | VN Partisan | 2,250 tonnes | Chartered |
|  | Training ships | VN Rebel |  | Chartered |
Question:
which class has the most displacement in tonnes?
Answer:
UT515 class