单项选择题
A.Compilation fails.
B.An exception is thrown at runtime.
C.The variable first is set to null.
D.The variable first is set to elements[0].
单项选择题 Given two files， GrizzlyBear.java and Salmon.java： If both classes are in the correct directories for their packages，and the Mammal class correctly defines thefindSalmon（） method， which change allows this code to compile？（）
单项选择题 Given： When line 14 is reached， how many objects are eligible for the garbage collector？（）
单项选择题 Given： What is the result？（）