scientists have created the world's smallest "snowman",( )ab

Scientists have created the world's smallest "snowman",( )about a fifth of the width of a human hair.
A measuring B measures C measured D to measure
答：最佳选项是A.
measuring about a fifth of the width of a human hair 是现在分词短语,是非限制性定语
相当于 非限制性定语从句 which measures about a fifth of the width of a human hair.
其逻辑主语是snowman,measure在这里和weigh的用法是一样的,表示“量起来有.”
不用被动语态.