You observe the lower limb of the Sun at a sextant altitude (hs) of 58°06.6' on 5 April. The index error is 1.0' off the arc. The height of eye is 55 feet (16.8 meters). What is the observed altitude (Ho)?

Correct Answer: Option B — 58°15.8'

Correct the sextant altitude by applying the index error (off the arc is additive), dip correction for 55 feet, and the Sun's altitude correction from the Nautical Almanac. Summing these values yields an observed altitude (Ho) of 58°15.8', adhering to the standard reduction steps outlined in Bowditch.