a$)$ List and explain $($in one sentence each$)$ the three components of standard template library $($STL$).$

b$)$ How to handle "divide by zero" exception with try catch and throw statements. Explain with the help of a program.

c$)$ Explain in brief the purpose of each of the following modes:

I. $\text{'}$ ios::out

IL ios::in

III. ios::app

IV$.$ ios::ate

d$)$ WAP in C$++$ to count the number of words in a given file.