Answer right or wrong. If the answer is wrong, provide the correct answer

1- The optimal portfolio of the investor taking the risk lies in a point of contact between the effective limits and the benefit curve according to the highest possible level of benefit. ( )

2- Tilt the effective boundary curve steadily as we move downward ( )

3- A portfolio is considered effective only if no second portfolio has the same return but has a lower risk level ( )

4- If you want to study the effect of adding shares on the portfolio, you should only consider the correlation factor of the new stock with other stocks ( )