If statement 4 is true, then it means that there are some colors that are not pleasant. However, this does not give any information about whether all colors are pleasant (statement 1) or whether some colors are pleasant (statement 2). Therefore, we cannot conclude that options 1 or 2 are true. Similarly, statement 3 cannot be concluded as true based on statement 4 alone. Therefore, the correct option is option 4: "Some colors are not pleasant."