Which of the following statements regarding marginal costing are correct? $1$ Calculations use both fixed costs and variable costs only. $2$ Calculations use variable costs only. $3$ Its use should be limited to long-term planning decisions only. $4$ Its use should be limited to short-term planning decisions only.
- A$1$ and $3$
- B$1$ and $4$
- C$2$ and $3$
- D$2$ and $4$