Why is Option 4 more expensive than the others?

Question 1

A. It has state of the art surveillance.

Answer

A. It has state of the art surveillance.

Question 2

C. It includes a one year data archive.

Answer

C. It includes a one year data archive.

Question 3

B. It has video cameras.

Answer

B. It has video cameras.

Question 4

D. It offers a back-up system.

Answer

D. It offers a back-up system.

Câu hỏi: Why is Option 4 more expensive than the others?