You observe the lower limb of the Sun at a sextant altitude (hs) of 28°24.7' on 17 May. The index error is 1.5' off the arc. The height of eye is 86 feet (26 meters). What is the observed altitude (Ho)?

Correct Answer: Option B — 28°31.5'

Apply corrections to the sextant altitude (hs) in the following order: Index Error (1.5' on the arc is additive), Dip (based on 86 feet), and the Sun's altitude correction (Refraction, Parallax, and Semi-diameter). Summing these values according to Bowditch Table A2 yields an observed altitude (Ho) of 28°31.5'.