Why Pink Ball is preferred over Red Ball for Day-Night Cricket test matches?

Test matches with usual morning to evening schedule are played with a red ball. In case of Day/Night Tests, the visibility factor comes into the picture as they are played under artificial lights, and hence, pink coloured ball is used.
The red ball loses shine and colour and appears brown in colour as the play progresses, making it difficult for the batsmen to spot it under floodlights. The pink balls have better visibility and lose their colour and shape more slowly, thus, they are preferred for Test under lights.

There were experiments with yellow, orange and pink balls, and there was even a suggestion to play with an improved white ball that could last 80 overs with the players wearing coloured kits but white ball doesn’t last even 50 properly, forget 90 overs as in test match.