At about GMT 1436, on 3 December, the lower limb of the Moon is observed with a sextant having an index error of 2.5' on the arc. The height of eye is 32 feet. The sextant altitude (hs) is 3°38.8'. What is the observed altitude?

Correct Answer: Option B — Ho 4°29.1'

Applying Nautical Almanac data for December 3, sextant altitude is corrected for index error (+2.5'), height of eye dip (-5.6'), and semi-diameter, parallax, and refraction corrections from the lunar tables, resulting in an observed altitude (Ho) of 4°29.1'.