In the given situation a functional organisation structure would be more suitable. The following points justify the use of functional organisation structure.
1. As it is a large organisation proper departmentalisation would help in improving overall managerial efficiency and degree of control over various activities.
2. The organisation is dealing with diverse functions simultaneously, thereby requires high degree of coordination. This can be achieved in a better manner through clear division of activities in various departments as done under functional structure.
3. Functional structure would promote specialisation which would help in performing the diverse functions in a better manner.