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:
| Model | Specification | Build date | Total produced | Wheel arrangement | Prime mover | Power output |
| --- | --- | --- | --- | --- | --- | --- |
| RS-1 | ME1000R (E-1641A) | 1954 | 3.0 | B-B | 6-539T | hp (kW) |
| RS-2 | ME1500R (E-1661B) | 1946–1950 | 9.0 | B-B | 12-244 | hp (kW) |
| RS-3 | ME1600R (E-1662, E-1662A, E1662B) | 1951–1956 | 146.0 | B-B | 12-244 | hp (kW) |
| RS-10 | DL-700 | 1954–1957 | 128.0 | B-B | 12-244 | hp (kW) |
| RS-11 | DL-701 | 1963–1964 | 75.0 | B-B | 12-251B | hp (kW) |
| RS-18 | DL-718 | 1956–1968 | 351.0 | B-B | 12-251B | hp (kW) |
| RS-23 | DL-811A | 1959–1966 | 40.0 | B-B | 6-251C | hp (kW) |
Question:
Which prime mover had a Model of rs-18?
Answer:
12-251B