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 D — 58°15.8'

Apply index error 1.0' (off the arc) to hs 58°06.6' to get 58°07.6'. Subtract dip for 16.8m (-7.2') and add the April Sun altitude correction (+15.4'). The resulting Ho is 58°15.8'. This follows standard celestial navigation procedures for correcting sextant observations to the observed altitude.