I don't understand this sentence.

3 For an organisation of your choice undertake the same exercise as in questions 1 and 2 above.

Your sentence lacks a comma after choice. It basically means

For an organisation of your choice, do the same exercise as in questions 1 and 2.

I'm not sure what the for an organisation of your choice part refers to though.

It is asking you to do the same as you did in questions 1 and 2, but this time do it "for an organisation of your choice", i.e. for any organisation that you like to choose. Exactly what it means to do the exercises "for" an organisation of your choice depends on the nature of the exercises. Probably it means that the organisation should in some way be the topic or focus of the answers. It could a

Do not double-post, Silencio. Be patient and wait for a response. Habitual double-posters lose their membership privileges.