Answer:
a. Most of the time we provide our information on different platforms on internet, that platforms provides us password to make sure that only the person knows your password can access your information. After getting password from some particular website, we assume that our information is secured now and secret from other users that also using that website. So we can say that Passwords is required to keep the information secret.
b. We want to make sure that our information should be secret from those people who can create problem for us or can be harmful in terms of life and money. These peoples are known as hackers. That may use our information for some purpose that can be harmful for us or our families. These people can use these information to steel our money or personnel information.
c. We sign privacy policy certificate while creating account on the website. That certificate is a legal document that is used to maintain the privacy of the users. But we can't say, our whole information is secure.