Opening principles

The three major opening principles are:

• Develop pieces as quickly as possible
• Castle as early as possible
• Control as much of the center as possible

Looking at the four given moves in order:

• a3 does not develop a piece, prepare castling, or challenge the center at all. It is effectively a wasted move.
• Bc4 achieves all three purposes: it develops a piece to a strong square, prepares kingside castling by moving out of the way, and takes control of the key central square d5.
• Qe2 harms White's development as it blocks the light square bishop, does not aid much in castling, and only indirectly affects the center.
• c4 takes some control of the center, but does not develop a piece and does not prepare castling.

Overall, only Bc4 is consistent with opening principles.

There can be many different openings played from this position, and no single move is absolutely good or absolutely bad. Let us look at why the other 3 options are unfavourable for white, and why $\text{Bc4}$ is a progressive move.

$\text{c4}$ could possibly be aiming at either playing $\text{c5}$ at some point or $\text{b4 b5}$ (providing enough support to both the options before execution). However this doesn't seem to put any pressure on black and is simply allowing black to advance his minor pieces faster. Moreover, this move allows black to play $\text{Nd4}$ , which is an unbelievably strong post for the black knight. If the white knight captures the black knight, black recaptures with the pawn gets a passed pawn on the d file, which can prove useful to black in the middlegame and endgame. Also, $\text{c4}$ blocks off the open diagonal for the white bishop. So, even though $\text{c4}$ is a legitimate move, it is highly in favour of black.

$\text{a3}$ aims at preventing black from playing $\text{Nb4}$ . This is useless at the moment, since $\text{Nb4}$ isn't very advantageous for black.

$\text{Qe2}$ as mentioned in the other solution, is a progressive move, but blocks off the white bishop, hindering the progress towards castling king side.

$\text{Bc4}$ is advantageous in four ways since it accomplishes 4 opening strategies at the same time.

• Bring your minor pieces into the game early
• Concentrate on control of the center
• Free space on either one side for castling.
• Hinder your opponents progress in the opening (Prevents black from playing $\text{b5}$ or $\text{d5}$ )

Also, black does not have an immediate move to kick the white bishop out of $\text{c4}$ .

In reality, any move will do since this is just the opening. But in theory, Bishop to e4 will give a chance for white to castle early, at the same time attacking the knight. But in real chess game my move is Bishop to e2. From the choices, c4 is also a good move.

Bishop to c4 clears the lane for kingside castle. The bishop on c4 is eyeing on square f7. After that white can play Knight to g5 (optional).

A good goal in chess openings is to establish your pieces in the center of the board.

You want to move your back line pieces to the center.

You could move either the Queen or the Bishop. However, it is not a good idea to move the queen because the move listed in the answer choices would block your own bishop.