The total amount of people surveyed is 50, that means 30% of them is 15. Based on the choices given, you find out which color groups add up to 15.
The first choice PInk, Orange, and Green has 14 people so that can't be the answer.
The second choice Green and Blue has 16 people so that can't be the answer.
The third choice Red and Purple has 15 people so that is our answer.
The fourth choice Black and Purple has 14 people so that can't be the answer.