Vertically polarized microwaves traveling into the page are directed at each of three metal plates (a, b,

Question:

Vertically polarized microwaves traveling into the page are directed at each of three metal plates (a, b, c) that have parallel slots cut in them.
(a) Which plate transmits microwaves best?
(b) Which plate reflects microwaves best?
(c) If the intensity transmitted through the best transmitter is I1, what is the intensity transmitted through the second-best transmitter?