What techniques did Ferdinand and Isabella use to centralize their authority?

What techniques did Ferdinand and Isabella use to centralize their authority?
 
  a. They sidelined the rebellious nobility by awarding titles to new nobility who were loyal to them.
  b. They established an entirely new administrative network who were loyal only to them.
  c. They arrested rebellious nobility and executed some as an example to the rest.
  d. They brought a lot of money into the country from their colonial interests and bought the nobility's cooperation.
  e. Along with the Jews and the Muslims, they expelled from Spain anyone who challenged their authority.