If a player receives the ball while touching a knee to the floor and subsequently stands up, is this a legal play?

In this situation, the correct response is that it is a legal play for a player to receive the ball while touching a knee to the floor and then stand up. A player is allowed to catch the ball while on the floor as long as they are not considered to be downed (e.g., both knees or other body parts besides feet touching the floor). When the player catches the ball, they may then get up and proceed as long as they do not violate any other dribbling or traveling rules upon standing up.

If the player rises from the floor with the ball in their possession without dribbling, there is no traveling violation, provided they pivot correctly or dribble the ball before making a further move. Therefore, the player's action of simply standing up after receiving the ball while touching their knee to the floor does not constitute a traveling violation as long as they maintain control of the ball during the transition.