A strategy of "planned ignoring" is MOST likely to be effective in reducing which kind of student conduct?

attention seeking behavior

Explanation:

Planned ignoring is a procedure which is designed to eliminate or decrease an inappropriate behavior of a student by withdrawing the reinforcer abruptly which is responsible for maintaining the behavior.

For a conduct of attention seeking behavior of a student, the strategy used to correct their behavior is "planned ignoring". With this method, a student is given less attention for engaging in any misbehavior but providing attention ti him when he is not engaged in any kind of misbehavior.

Thus the answer is - - "attention seeking behavior".