The question asks us to find the equivalent code for the word 'OCEAN' based on a given pattern used for other words.

To determine the pattern of the encoding, let's analyze the given examples:

• The word 'SHAKE' is transformed into 'HKSAE'.
• The word 'RIVER' is transformed into 'RRVEI'.

Now, let's break down the transformation pattern for each example:

1. For 'SHAKE' to 'HKSAE':
   • 'S' moves to the 3rd position.
   • 'H' moves to the 1st position.
   • 'A' moves to the 4th position.
   • 'K' moves to the 2nd position.
   • 'E' stays in the 5th position.
2. For 'RIVER' to 'RRVEI':
   • 'R' stays in the 1st and 2nd positions.
   • 'I' moves to the 5th position.
   • 'V' stays in the 3rd position.
   • 'E' moves to the 4th position.

Analyzing these, the apparent pattern involves selectively rearranging letters and positioning them in a new order using a consistent rule. To derive the pattern, isolate the two transformations to determine positions other than the 'exchanged' pairs and unchanged static letters:

• Upon inspection, the pattern for the current position seems consistent with:
  • 1st letter goes to the last position.
  • 2nd letter moves forward or stays.
  • 3rd letter finds a matching or is maintained based on the next similar position.
  • The position having duplicity retains the second identical letter.
  • Final letters rearrange such that the start gets pushed to the end.

Given these observations, transforming 'OCEAN' would follow:

1. 'O' moves to the last position.
2. 'C' and 'E' maintain similar cool-character configurations.
3. 'A' takes a mid or advanced spot pertaining to its secondary position.
4. 'N' can be integrated at a non-back, non-front, auxiliary position.
5. Resulting in the coded word 'CNAEO'.

Thus, the encoded answer for 'OCEAN' is CNAEO, making the correct option:

CNAEO