$3\mathrm{.}1$ The work breakdown structure for building a house

$($levels $1$ and $2)$ is shown below:

Site

Preparation Masonry Carpentry Plumbing Finishing

House

Level $2$

Level $1$

a$)$ Add two level $3$ activities to each of the level $2$ activities to provide more detail to the WBS$.$

b$)$ Select one of your level $3$ activities and add two level $4$ activities

below it$.$