When publishing an update to your application to the market, the following must be taken into consideration:

When publishing an update to your application to the market, the following must be taken into consideration:
A . The package name must be the same, but the .apk may be signed with a different private key.
B . The package name does not have to be the same and the .apk can be signed with a different private key.
C . The package name must be the same and the .apk must be signed with the same private key.
D . The package name does not have to be the same, but the .apk must be signed with the same private key.

View Answer

Answer: C

Explanation:

You should sign all of your apps with the same certificate throughout the expected lifespan of your applications.

App upgrade: When the system is installing an update to an app, it compares the certificate(s) in the new version with those in the existing version. The system allows the update if the certificates match. If you sign the new version with a different certificate, you must assign a different package name to the application ― in this case, the user installs the new version as a completely new application.

References: http://developer.android.com/tools/publishing/app-signing.html