Step 1: Identify the relationship type in the given pair: MYOPIC and SHORT-SIGHTED are synonyms, where the first is a more formal or literary word and the second is its everyday, plain-language equivalent.
Step 2: Apply this same synonym relationship to OBSTINATE, which means stubbornly sticking to one's own opinion or course of action, even against good reasons to change.
Step 3: Check each option for whether it means the same thing as obstinate. 'Flexible' describes willingness to change, the opposite of obstinate. 'Generous' relates to giving, unrelated to stubbornness. 'Cautious' relates to carefulness, not to refusing to change one's mind.
Step 4: 'Stubborn' is the everyday, plain-language synonym for 'obstinate', exactly matching the same synonym pattern as myopic and short-sighted.
Correct option: (4) Stubborn.