Which of the following could be the most suitable title

A．Color probably has an affect on us which we are not conscious of.
B．Yellow fire engines have caused many bad accidents in some advanced communities.
C．People exposed to pure blue start to breathe more slowly.
D．The psychology of color is of some practical use.

A．associated with the time of day
B．dependent on our character
C．linked with our primitive ancestors
D．partly due to psychological factors