Explanation
A Petabyte (PB) is a unit of digital information storage used to measure very large amounts of data. In the binary system (base-2), which is most commonly used in computing, 1 Petabyte is exactly equal to 1024 Terabytes (TB). Hence, option A is correct.

• In terms of smaller units, 1 Petabyte is equivalent to 1,048,576 Gigabytes (GB) and approximately 1 quadrillion bytes (specifically 1,125,899,906,842,624 bytes).
• 1024 Zettabytes is equal to 1 Yottabyte (YB), which is a much higher order of magnitude than a petabyte. Hence, option B is incorrect.
• 1024 Yottabytes is often referred to as a Brontobyte or Hellabyte in theoretical computing, representing an astronomical scale of data far beyond a petabyte. Hence, option C is incorrect.
• 1024 Gigabytes is equal to 1 Terabyte (TB), which is the unit immediately below the petabyte in the storage hierarchy. Hence, option D is incorrect.

The relationship between these units follows a power of 2 progression, where each subsequent unit is 2^10 (which is 1024) times the size of the previous unit.
Important Points

• Bit: The smallest unit of data, representing a logical state with one of two values, 0 or 1.
• Nibble: A group of 4 bits or half a byte.
• Byte: Consists of 8 bits and is the standard unit used to represent a character such as a letter, number, or symbol.
• Exabyte (EB): The unit immediately following the Petabyte. 1 EB = 1024 PB. Global internet traffic is often measured in Exabytes per month.
• Conversion Table Summary:
  • 1024 B = 1 KB
  • 1024 KB = 1 MB
  • 1024 MB = 1 GB
  • 1024 GB = 1 TB
  • 1024 TB = 1 PB