Answer:
Phased installation
Explanation:
The name of this strategy is phased installation. Phased installation (or phased implementation) occurs when an existing system is replaced by a new one. However, unlike most implementations, this takes place in stages. This has several advantages. First, it allows you to test the system. If there is a problem with it, it is easier to revert back to the old strategy. Moreover, if employees need to adopt this new system, it allows them to get used to it slowly while still being able to access the previous one.
Answer:
solution attached.
Explanation:
Also, the tetha time complexity of T_upper would be 
The Carbon Monoxide will build up in the inside of the car by venting through, causing the passengers to breathe it. It will first make them ill, then kill them. They cannot detect this gas