Final answer:
Blackberry devices connect using a RIM wireless modem, and applications for the platform must be digitally signed for security purposes.
Step-by-step explanation:
Devices connect to Blackberry require a RIM wireless modem. Applications developed for Blackberry must be digitally signed to identify the developer. Therefore, the correct answer to the question is:
a) RIM wireless modem - Signed digitally in order to identify the developer
Blackberry devices use a proprietary technology for connectivity, and applications must go through a security process which includes a digital signature by the developer to ensure authenticity and to protect the users and platform from malicious software.