Which three items should the administrator take to consideration before installed he managed package?

An administrator has found a free app on the AppExchanged and would like to install it.

Which three items should the administrator take to consideration before installed he managed package? Choose 3 answers
A . Custom objects and custom fields used by the app count against the org’s limits.
B . Managed apps do not undergo a formal security review by Salesforce.
C . Apps may require certain Salesforce editions or features to be enabled.
D . Apps may require external, third-party web services to function properly.
E . Apps must be installed in production before the app can be installed in a sandbox.

Answer: C,D,E