Choose the word (A, B, C or D) that best fits the blank space in the following passage.

There are many ways to cut the (19)_____ of your power bill in your home. Take a look at the way we choose computers (a laptop or a desktop computer). A laptop is a computer that is small enough (20)_____ carried around easily and is flat when closed, While a desktop computer is the one that fits on a desk but that is not easily moved from place to place.

Regardless of their convenience difference, choosing a laptop or a desktop computer may result in a significant difference in energy (21)_____. I'm writing this by using a laptop with power (22)_____ features switched on —using around 50 watts maximum. Back some years ago, I would work with a desktop computer with a 17” CRT screen —around 300 watt all told.

The following are some rough (23)_____ based on coal fired power generation for just the computer aspect:

- Laptop = 50w x 10 hours a day x 365 days = 185.5 kilowatt hours

- Desktop = 300w x 10 hours a day x 365 = 1095 kilowatt hours

In the case of cal fired electricity, each kilowatt you save not only puts (24)______ back into your pockets, but also avoids up to 1.5 pounds of carbon dioxide emission being generated.