For everyone who is not able to understand this problem, just have a look here:

When you select “Safely Remove Drive” the device gets unmounted and powered down. You need to have a look at the bug report at Gnome Bugzilla where the GNOME dev explains why they need to put all three options.

A furthur explanation is given as

First, some terminology:

"safely remove drive" is intended to mean "power down the drive so it is safe
for removal". Right now this is done by suspending the USB port but there's a
patch pending for 2.6.32 for powering down the port completely. The effect is
that the device powers off, specifically that leds on the device (if any) will
be powered off. Many people have asked for this feature, certain (rare) pieces
of hardware seems to require it.

(There might be a better term for option than "safely remove drive" but it's a
bit late to change it for 2.28.x. - and, for the record, it's similar in name
and functionality to what Windows is using.)

Second, "eject" means "eject the media" (for e.g. optical drives) or "make the
annoying 'not safe to remove' banner on the device go away" (for phones, ipods,
ebook readers etc.).

Third, "unmount" means well.. our beloved geek-word... also known as 'umount'.
Windows, I'm told, nowadays uses "Dismount". We could remove this geek-comfort,
it might be nice.

I can understand the problem, but keeping 3 options is nothing more than confusing the users. Even people who use Linux on day-to-day basis also think for a second when encountered with this option list.

We are here to make Ubuntu easier to use for the masses. This is surely a roadblock even though keeping all the three options might be necessary.

The simplicity and non-confusing nature of windows was the key reason of the growth if you step out of the anti-MS campaign. Non-techies never get confused with removing media on windows. Why is Ubuntu behind?