You observe the lower limb of the Sun at a sextant altitude (hs) of 37°47.2' on 11 October. The index error is 3.0' off the arc. The height of eye is 63 feet (19.2 meters). What is the observed altitude (Ho)?

Correct Answer: Option D — 37°57.5'

Correct the sextant altitude by applying the index error (+3.0' for off the arc), the dip correction for 63 feet (-7.9'), and the combined altitude correction for the Sun's lower limb (+15.2'). Summing these values to the hs of 37°47.2' yields an observed altitude (Ho) of 37°57.5'.