If altitude bubble is provided both on index frame as well as on telescope of a theodolite, then the instrument is levelled with reference toi) altitude bubble on index frameii) altitude bubble on index frame if it is to be used as a leveliii) altitude bubble on telescopeiv) altitude bubble on telescope if it is to be used as a levelThe correct answer is

• A. only (i)
• B. only (iii)
• C. both (ii) and (iii)
• D. both (i) and (iv)

Answer: (D)