Exam 312-50v11 topic 1 question 19 discussion

C : Using Unicode representation, where each character has a unique value regardless of the platform, program, or language, is also an effective way to evade IDSs. For example, an attacker might evade an IDS by using the Unicode character c1 to represent a slash for a Web page request.

IDS Evasion Techniques Unicode Evasion Technique Unicode is a character coding system to support the worldwide interchange, processing, and display of written texts.
 Taking this as an advantage, attackers can convert attack strings to Unicode characters to avoid pattern and signature matching at the IDS. (P.1551/1535)

It says "web world" so its clearly C

The primary purpose of port knocking is to prevent an attacker from scanning a system for potentially exploitable services by doing a port scan, because unless the attacker sends the correct knock sequence, the protected ports will appear closed.

Answer C, Unicode is a character coding system that supports encoding, processing, and displaying of written texts for universal languages to maintain consistency in a computer representation. Several standards, such as Java, LDAP, and XML, require Unicode, and many OS and applications support it. Attackers can implement an attack by different character encodings known as “code points” in the Unicode code space. The most commonly used character encodings are Unicode Transformation Format (UTF)-8 and UTF-16.