💡 Detailed Explanation
The grammar pattern '～ものを' expresses dissatisfaction or regret that something didn't turn out as expected, similar to 'if only... but...'. '易々と' (yasuyasu to) means 'easily' or 'without effort'. The correct word order is 「だった」「ものを」「易々と」「逃してしまう」. Therefore, the word that goes in the star position is 「易々と」.