Losses in photonic crystal fibers are reduced to a level of . . . . . . . .

The correct answer is: A. 0.1dB/km

Photonic crystal fibers (PCFs) are a type of optical fiber that has a regular structure of air holes in a silica glass matrix. This structure allows PCFs to have very low losses, typically around 0.1dB/km. This is much lower than the losses of conventional optical fibers, which are typically around 1dB/km.

The low losses of PCFs make them ideal for use in long-distance optical communications. They are also used in other applications, such as sensing and medical imaging.

The other options are incorrect because they are higher than the actual losses of PCFs.