This question asks you to develop an ER diagram from the narrative below.

The information system, which you will analyse, aims to assist a student recreational skiing society, which needs to deal with members and to organise events for members. At present the system is paper$-$based, but in future it is hoped to develop a computer$-$based system.

The society secretary uses the system to record information when a new member joins the society: the information includes the member's name, term$-$time address, vacation address, phone number, email, and the different varieties of skiing in which they are interested $($for example, Peter Williams may have interest in the beginner's cross$-$country, the intermediate downhill, and the expert bobsled$).$ Usually, members join for a period of one winter season by paying a fee, and at the end of that time the secretary can extend their membership if they pay another fee; alternatively, some members choose to join for longer periods $($the fee they paid is then reduced, compared to paying for seasons one by one$).$ The event manager uses the system to arrange a ski trip, which occurs over a particular period $($such as the long weekend of October $4$ to October $6$ inclusive$),$ includes accommodation at a particular address, and also has one or more sessions of various varieties of skiing, each located on a particular area of a ski slope; for example, one meeting may involve three sessions of intermediate downhill held on Piste $x,$ Piste $Y$ and Piste $Z$ respectively, and one session of beginner's downhill held on Piste X$.$ The event manager schedules each session with the appropriate number of participants from among the members who are interested in that variety of skiing. The cost of a meeting for the society depends on the number of members who are involved $($as the accommodation fee is charged per person$)$ as well as on the number of sessions, and the variety of each $($because each different session requires booking an appropriate area of the ski slope$).$ The club treasurer uses the system to obtain reports on the total cost of the trips held during each season, and on the total fee income from memberships for that season.