$($a$)$ There are Include and Extend associations between use cases in the

Use Case UML diagram. Provide an explaination when each type is

intended to be used.

$[5$ marks$]$

$($b$)$ An Online Shopping System is being developed. The system can keep

track of sellers, customers, items, orders, transactions, delivery and the

relationships between them. Based on the information given in the

project description,

$1.$ Identify main actors $($min $2)$ and possible important use cases

$($min $6)$ of the system. Draw a Use Case diagram to illustrate the

interactionsbetween the actors and the use cases identified.

$2.$ Draw a Sequence Diagram using one of the identifed use cases in

the Use Case diagram.

$3.$ Draw a class diagram to illustrate system objects, specifying the

relationship between classes $($provide at least $2$ classes$)$