Interactive Home-security Systems
Tarik Celebi, who lives in San Francisco suburb, takes his home-security system with him to work, to dinner, just about anywhere．By his cell phone, he "arms" his home-security alarm from his car before he leaves for work．During his workday, he gets e-mail alerts every time his front door opens, even though he's miles away．If the door opens at an unusual time -say midday when no one should be coming or going - he can order a 30-second video clip（片段） from the camera that watches the door．If it's just his  mother-in-law getting a package delivery, no worries．
Celebi is one of the first users of the latest interactive home-security systems．In addition to sounding alarms when the house is broken into and notifying homeowners or police, as traditional systems do, the interactive systems give users new ways to remotely control their systems and their home environment．Different from traditional home-security alarms, which homeowners typically have to press buttons on a keypad to turn on before they leave their homes, the interactive systems enable consumers to arm and disarm systems from smart phones, iPads and PCs, no matter where they are．
Most traditional systems are set up to sound an alarm if doors or windows are opened． The interactive systems give homeowners more options．For example, users can elect when they want to be notified．They might want an e-mail or a text every time a door is opened, or only during the hours of 3 to 4 p．m．, when kids come home from school．Like Celebi, they can add cameras and get video clips when doors open．That could be helpful in making sure kids aren't bringing friends home when they're not supposed to．
Nationwide, about 20% of homes have．traditional home-security systems．About half stop using them because they tire of the trouble．Being able to arm systems even while dashing to the subway or while at work will increase their usage of the new interactive systems．Although the new functions add costs to home security, the interactive-systems are believed to push home-security systems' usage rates closer to 30%, which would be a big movement for an industry that's been largely stuck at 20% for the past decade．"We all know it's going to get bigger, though we don't know how long it's going to take," Eric Taylor, an officer from San Francisco Security Department says．
What may Celebi first do if his front door opens at a wrong time when he is away?

A．Inform the police．	B．Call his mother-in-law．
C．Arm the security alarm．	D．Observe through video．

The interactive systems enable the user to ______．

A．improve his home environment remotely

B．lock his house's door while he is miles away

C．operate the home-security systems at any place

D．sound the alarm and inform the police at the same time

What's the advantage of the interactive systems over the traditional ones?

A．They are cheaper．

B．They are easier to set up．

C．They can give quicker reaction．

D．They have more ways to inform the users．

What is the last paragraph mainly about?

A．The importance of security industry．

B．The functions of the interactive alarms．

C．The popularity of home-security systems．

D．The market potential of the interactive systems．