The correct answer is option C: 1, 2, and 4 only.

Shell mould casting, also known as shell molding or shell molding casting, is a casting process that uses a resin-coated sand shell to form the mold. This process offers several advantages over other casting methods. Let's discuss each advantage in detail:

1. Close dimensional tolerance: Shell mould casting provides close dimensional tolerances, meaning that the cast parts can be manufactured with high precision and accuracy. The use of a shell mold allows for greater control over the final dimensions of the cast part, resulting in minimal dimensional variations. This advantage is particularly important in industries where tight tolerances are required, such as aerospace or automotive.

2. Good surface finish: Shell mould casting produces castings with a smooth and consistent surface finish. The resin-coated sand shell used in this process helps to create a mold cavity with excellent surface quality. As a result, the cast parts have a clean and polished appearance, requiring minimal post-processing or finishing operations.

3. Low cost: Shell mould casting is a cost-effective casting method. The process uses readily available materials, such as sand and resin, which are relatively inexpensive compared to other mold materials. Additionally, the use of reusable shell molds reduces the overall production costs as compared to traditional sand casting, where a new mold is required for each casting. The low cost of shell mould casting makes it an attractive option for large-scale production runs.

4. Easier: Shell mould casting is relatively easier compared to other casting methods. The process involves fewer steps and requires less equipment and manpower. The use of pre-coated sand shells simplifies the mold-making process, reducing the time and effort required to produce molds. This advantage makes shell mould casting more efficient and less labor-intensive than some other casting techniques.

In conclusion, shell mould casting offers advantages such as close dimensional tolerance, good surface finish, and ease of use. These advantages make it a preferred choice for many applications where precision, aesthetics, and cost-effectiveness are important factors. Therefore, option C: 1, 2, and 4 only is the correct answer.