* ADSL Interleave Mode :
* Interleave mode is used in ADSL to improve error correction by interleaving data bits before transmission.
* This process introduces additional latency (delay) but enhances stability by reducing the impact of impulse noise.
* Why B?
* Better stability : Interleaving spreads errors across multiple frames, making it easier to correct them.
* Longer delay : The interleaving process adds latency due to the time required to reorder data bits.
* Other Options :
* A : Incorrect because interleave mode improves stability, not worsens it.
* C : Incorrect because interleave mode increases delay, not reduces it.
* D : Incorrect because interleave mode improves stability.
Thus, the correct answer is B .
References:
* HCIA Huawei ACCESS Official Documentation , Chapter: ADSL Modes.
* ADSL Interleaving and Fast Path by Huawei.

File Transfer Protocols:
FTP (File Transfer Protocol): Provides reliable file transfer with high speed and ease of use.
TFTP (Trivial File Transfer Protocol): Lightweight but lacks security and reliability features.
SFTP (Secure File Transfer Protocol): Secure but slower due to encryption overhead.
Recommendation for Upgrades:
During access network upgrades, large files (e.g., firmware images) need to be transferred quickly and reliably.
FTP is recommended because it balances speed, reliability, and ease of use.
Why TRUE?
The statement correctly identifies FTP as the recommended protocol for file transfers during upgrades.
Thus, the correct answer is A.