答案：A.
解析：从句型上看,该句为感叹句.感叹句是由感叹词what或how引导的感叹句.
what修饰名词或名词短语,有以下两种形式：
1.What+a(an)+（形容词）+单数可数名词+主语+谓语!
或是：What+名词词组+主语+谓语!
如：What an apple this is!What a fine day it is!
2.What+(形容词）+可数名词复数或不可数名词+主语+谓语!
What kind women they are!What nice music it is!
how用来修饰形容词、副词或动词.其结构是：How+形容词（副词）+主语+谓语!
How hard the workers are working!
注意：当how修饰动词时,动词不跟着感叹词提到主语之前.
How the runner runs!
what与how引导的感叹句,一般情况下可以相互转换,转换后意义不变.如：
What an interesting story it is!==How interesting the story is!
What a beautiful building it is!==How beautiful the building is!
在口语中,感叹句的主语和谓语常常省略.如：
What a nice present!（省略it is）
How disappointed!（省略she is或其它可作本句主、谓的词语）