I need help please

Does anyone know what my spanish teacher means by this? i need to use plural forms of the verb ser. and she asked me to use a couple of adjectives to describe the boys collectively and then the girls collectively?

Fui al centro comercial vi unos tenis i los compre que compre?

How would you say “blue is better than green”? in spanish a. azul es mejor que verde. b. azul es peor que verde. c. azul es menos que verde. d. azul es más que verde