This question is confusing itself and that is why one CIC agent say mark NO and other say mark N/A. It is not lying or truthful issues. In one hand CIC says you can not leave any questions un-answard and in other hand they did not leave a box to put N/A.
There is many applicant who might have left this Qes open or may have marked YES when LINC taken or NO or might have marked N/A when not taken. However, even with confusion, if any one marked NO (where CIC says you have to provide alternate proof), CIC will not go hunt to ask why you marked NO? I think only during Interview if officer asks about this NO marking (not giving consent-which is very unlikely to ask) then just explain that I have not taken and thus marked NO and CIC agent also advised to put NO.. That's all.
Bottom line is, if the application is accepted and In Process then the language proof matter is closed...CIC has so many other questions in the application to go after.. My family applied last week of April with marking NO and as of today no response from CIC neither return or In Process (as they working on 15th April applications now), but in case of return incomplete applications, it would have been happened now as these days CIC returns those applications within 4-6 weeks..