(B) What is application object ?
Application object can used in situation where we want data to be shared across users globally.

(I)What’s the difference between Cache object and application object ?
The main difference between the Cache and Application objects is that the Cache object provides cache-specific features, such as dependencies and expiration policies.

(I)How can get access to cache object ?
The Cache object is defined in the System.Web.Caching namespace. You can get a reference to the Cache object by using the Cache property of the HttpContext class in the System.Web namespace or by using the Cache property of the Page object.

(A)What are dependencies in cache and types of dependencies ?
When you add an item to the cache, you can define dependency relationships that can force that item to be removed from the cache under specific activities of dependencies.Example if the cache object is dependent on file and when the file data changes you want the cache object to be update.Following are the supported dependency :-
√ File dependency :- Allows you to invalidate a specific cache item when a disk based file or files change.
√ Time-based expiration :- Allows you to invalidate a specific cache item depending on predefined time.
√ Key dependency :-Allows you to invalidate a specific cache item depending
when another cached item changes.