Step 1: Define Rare Earth Elements (REEs).
REEs include 15 lanthanides plus scandium and yttrium. Cerium is part of the lanthanide series.
Step 2: Evaluate the options.
Cerium (Ce) is a well-known REE.
Lithium, Titanium, and Cobalt are transition or alkali metals but not classified as REEs.
| Feature in mine plan | Symbol | ||
| P | shaft | 1 | ![]() |
| Q | staple shaft | 2 | ![]() |
| R | Abandoned shaft | 3 | ![]() |
| S | Abandoned staple shaft | 4 | ![]() |

Pressure head characteristic of a mine fan and a mine characteristic curves are shown in the figure below:

Match the points with their corresponding nomenclatures