Answer:
Nancy's private key
Explanation:
She's receiving it. That means Matthew used her public key to encrypt it. She should decrypt it using her private key. Watch this video for clarification :)
Watch The Internet: Encryption & Public Keys on the big video site which cannot be named on brainly :p
Doctor or teacher or an engineer
Here are some of the computers used in the first generation of computers:
ENIAC
EDVAC
UNIVAC
IBM-701
IBM-650
These are some of the first computers ever that led to today's computers.