Correct option is C
 A group of 
  4 bits is called a 
  nibble. It is half of a 
  byte, which consists of 8 bits. Nibbles are commonly used in 
  binary and hexadecimal data representation.
  
  
  Important Key Points: 
  
 1. 
  1 Nibble = 4 bits, representing a single 
  hexadecimal digit.
  
 2. A 
  byte is made up of 
  2 nibbles or 
  8 bits.
  
 3. Nibbles are useful in 
  low-level programming and digital electronics.
  
  
  Knowledge Booster: 
  
 · 
  BYTE – Composed of 
  8 bits, not 4.
  
 · 
  WORD – A 
  CPU-specific unit that may be 16, 32, or 64 bits depending on the system.
  
 · 
  K.BYTE (Kilobyte) – Equals 
  1024 bytes, not related to bit-level groupings.