user1371: 
As per subject, why Qd1 is the best move and all other moves for queen like Qd2 and Qd3 are not? I understand that it’s important to cover d column but why 1 and not 2 or 3?
Also why Rd1 is not a good move? 

user11609: Qd1 wins a piece attacking both d6 and h5.

user4362: Qd1 hits the bishop on d6 and the knight on h5. One of those will be won.
Btw, I think this a famous game between Larry Christiansen and Anatoly Karpov. Famous, of course for this early blunder. Here, you can see the whole game and maybe find out more about the players.

1371: <p><img src="https://i.stack.imgur.com/ISRwC.png" alt="enter image description here"></p>

<p>As per subject, why Qd1 is the best move and all other moves for queen like Qd2 and Qd3 are not? I understand that it’s important to cover d column but why 1 and not 2 or 3?</p>

<p>Also why Rd1 is not a good move? </p>
 11609: <p>Qd1 wins a piece attacking both d6 and h5.</p>
 4362: <p>Qd1 hits the bishop on d6 and the knight on h5. One of those will be won.</p>

<p>Btw, I think this a famous game between Larry Christiansen and Anatoly Karpov. Famous, of course for this early blunder. <a href="http://www.chessgames.com/perl/chessgame?gid=1069116" rel="noreferrer">Here, you can see the whole game and maybe find out more about the players.</a></p>
