John, ____ handwriting was very beautiful, was going to the contest, too. [ ]

A. of who

B. of which

C. who's

D. whose

对比实验是运用比较的方法来揭示事物的性质或变化规律的一种实验方法。课本中设计的下列实验属于对比实验的是

A．加热试管中火柴头

B．双氧水分解制取氧气

C．将二氧化碳通入紫色石蕊试液

D．水和空气的压缩实验