Answer: b. .alert-warning
Explanation: In Bootstrap, we can create predefined alert messages easily. Alerts are created with the .alert class followed by four contextual classes .alert-success, .alert-info, .alert-warning or .alert-danger.
Answer: b. .btn-link
Explanation: Bootstrap provides several predefined button styles, each serving its own semantic purpose.
E.g. .btn-link class is used to create a button as a link in bootstrap.
Answer: a. True
Explanation: Badges are numerical indicators of how many items are associated with a link. Badges can also be used inside the button elements.
<button type="button" class="btn btn-primary">Primary <span class="badge">5</span></button>
Answer: c. .navbar-right
Explanation: The .navbar-right class is used to right-align navigation bar button in Bootstrap.
Answer: b. .navbar-btn
Explanation: In Bootstrap, to add a button inside the navbar, we put .navbar-btn class on a button.
Answer: d. .img-thumbnail
Explanation: In Bootstrap the .img-thumbnail class is used to shape an image to a thumbnails.