the fact that the question states 3.1m suggests to me that you will be working at a height and even if the ladder was used to access the "roof void" what equipment would have to be used to access the workplace? seeing as it is a conduit run suggests that the work takes place over a distance agreed you are taking the term "access" literally and if it was purely just to get you into a "roof void" then yes i'd agree but then why would the question go on to say that conduit is going to be installed? Why just not say what access equipment is needed to gain access to a "roof void" or ceiling void as harry first mentioned a ceiling void could just be a false ceiling after all.