The OpenPgP encryption protocol stands for Open Pretty Good Privacy.

Synchronized versions of the collections in the Java Collections API allow ________ at a time to access a collection that might be shared among several threads.

a. any number of threads b. only one thread c. a maximum of two threads d. None of the above.

What is the error in the following code? Why is this wrong?

``` int f(int x) { int x; // code for function body } ```