絞る and 搾る: Wringing, narrowing candidates, and extracting liquid
Compare the two spellings read しぼる through cloth, candidates, lemon juice, and milk. Distinguish narrowing a candidate range from extracting liquid.
Wringing or narrowing with 絞る
絞る means to wring or narrow down. 「洗った布を両手で強く絞った。」 reports firmly wringing washed cloth with both hands. The cloth is the object.
The English translation of 「候補を三つに絞って詳しく比較する。」 is “We narrowed the candidates to three for closer comparison.” 絞って reduces the candidate range; it does not describe extracting liquid.
Squeezing or milking with 搾る
搾る means to squeeze or milk. 「半分に切ったレモンを手で搾りました。」 reports squeezing half a lemon by hand. The named object is a source of liquid.
「農場では毎朝、牛の乳を搾ります。」 says the cows are milked every morning on the farm. Milking is another use of 搾る.
A shared reading and different targets
Cloth with 絞る and lemons or milk with 搾る show representative object combinations. They do not create an exclusive cloth-versus-food spelling rule.
候補を絞る is the abstract use of reducing candidates. Narrowing to three for comparison does not report selecting a final candidate; follow the object and the stated further comparison.
Does 絞る in 候補を三つに絞って比較する concern extracting liquid or reducing the candidate range?
Show the answer and why
It reduces the candidates to three. The target differs from lemons or milk with 搾る, and narrowing for comparison does not itself report a final selection.