The problem seems to be the two non-pairs 'loose/lose' and 'choose/chose' In the first pair, the vowel stays the same (the same phoneme, that is) and the voicing of the fricative changes. In the second pair the voicing of the fricative remains unchanged, but the vowels are different. The spellings suggest they should be similar. The typo reinforces that. I wouldn't be at all surprised if the 2100 edition of a reputable dictionary agrees with the typo, and notes that a few users (especially those born before the turn of the 20th centiury) preserve the old anomalous spelling - just as there are still a few people who spell 'show' 'shew'. ;-)
b