Which is not a valid range?

In an array-based implementation of a heap, the number of array items that must be swapped to transform a semiheap of n nodes into a heap is ______.

a) n b) n + 1 c) log2n d) log2(n + 1)

In a wireless network, RF signals are sent and received by a ______________.

Fill in the blank(s) with the appropriate word(s).