Which of the following uses radio waves to transmit data signals over short distances?

Which one of the following packages provides encryption support?

a. org.json b. javax.* c. android.* d. junit.*

Answer the following statements true (T) or false (F)

1) Type constraints restrict the type of the argument supplied to a particular type parameter. 2) IComparable objects cannot, by default, be used with generic code. 3) If there's a constructor constraint, the type argument’s class must not provide constructors. 4) It's not possible to apply multiple constraints to a type parameter.