Please select the correct answer:

The first five questions use alphabet { = {a, b} and have exactly one correct answer. Recall that superscript plus means "one or more" and that zero counts as an even number. For this and the next two questions, say which prose description goes with the regular expression at top. The first char in a string has index 1, not 0. Regular expression: (aa U ab) + Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Nonempty strings with three times as many a's as b's b Nonempty strings in which the first and every other odd-indexed char is an a. Nonempty strings of even length in which the first and every other odd-indexed char is an a. Nonempty strings of even length in which the first and every other odd-indexed char is an a and the even-index chars alternate a and b. e Nonempty strings that either repeat aa one or more times or repeat ab one or more times