Which statement$/$s related activity$-$based costing is$/$are correct? Statement $1$: short$-$term variable overhead costs should be traced to products using volume$-$related cost drivers, such as machine hours or direct labour hours. Statement $2$: long$-$term variable production overhead costs are partly driven by the complexity and diversity of production work, as well as by the volume of output. Statement $3$: transactions undertaken by support department staff are the appropriate cost drivers for long$-$term variable overhead costs. Statement $4$: overheads should be charged to products based on their 'usage of an activity'. A product's 'usage of an activity' is measured by the number of cost drivers used by that activity.

a$.$

Statement $1$ only

b$.$

Statements $3$ and $4$

c$.$

Statements $1$ and $2$

d$.$

Statements $1,3$ and $4$