Seven men, A, B, C, D, E, F and G are standing in a queue in that order. Each one is wearing a cap of a different colour like violet, indigo, blue, green, yellow, orange and red. D is able to see in front of him green and blue, but not violet. E can see violet and yellow, but not red. G can see caps of all colours other than orange. If E is wearing an indigo coloured cap, then the colour of the cap worn by F is

Let's break down the clues step-by-step: 1. Men are A, B, C, D, E, F, G in a queue (from front to back). A person can see caps of those in front of them. 2. Colours: Violet (V), Indigo (I), Blue (B), Green (G), Yellow (Y), Orange (O), Red (R). Given: E is wearing an Indigo (I) coloured cap. So, E = I. Clue 1: D is able to see in front of him Green and Blue, but not Violet. * D sees A, B, C. So, Green and Blue are among A, B, C. * D does not see Violet. This means Violet is either D's own cap, or the cap of someone behind D (E, F, G). Clue 2: E can see Violet and Yellow, but not Red. * E sees A, B, C, D. So, Violet and Yellow are among A, B, C, D. * E does not see Red. This means Red is either E's own cap, or the cap of someone behind E (F, G). * Since E is wearing Indigo, Red cannot be E. So Red is F or G. Combining Clue 1 and Clue 2 for Violet: * From Clue 1: Violet is D, E, F, or G. * From Clue 2: Violet is A, B, C, or D. * The only position common to both is D. Therefore, D must be wearing the Violet cap. So, D = V. Now we have: D = V and E = I. Let's re-evaluate with D=V and E=I: * Clue 1 (D sees Green and Blue, but not Violet): D (Violet) cannot see his own cap, which is consistent. A, B, C wear Green and Blue (and one other colour). * Clue 2 (E sees Violet and Yellow, but not Red): E (Indigo) sees D (Violet), which is consistent. E also sees Yellow, so Yellow is among A, B, C. E does not see Red, so Red is F or G. From the above, we know: * A, B, C wear Green, Blue, Yellow (these are 3 distinct colours for 3 people). * D wears Violet. * E wears Indigo. * F and G wear the remaining two colours, which are Orange and Red. Clue 3: G can see caps of all colours other than Orange. * G is at the very end of the queue. G sees A, B, C, D, E, F. * If G sees all colours *except* Orange, it means Orange must be G's own cap. So, G = O. Now we have: * D = Violet * E = Indigo * G = Orange The colours used are Violet, Indigo, Orange. The remaining colours are Blue, Green, Yellow, Red. The remaining people are A, B, C, F. We established that A, B, C wear Green, Blue, Yellow. This leaves Red as the only remaining colour for F. Therefore, F wears Red. The final answer is C) Red.