Here’s a question no one was asking at the start of the summer: What’s showing at the movies? A few months ago, the response would have been “nothing, naturally.” And while the last couple of weeks haven’t exactly seen a record-breaking rush back to darkened theaters, the reopening of corporate chains at least gives us the option to see some movies the way they were intended. Here’s what you need to know. What’s playing? The selection is more limited than usual, but exhibitors are almost exclusively showing would-be blockbusters and cheaper, fan-favorite classics, given that they want to reach the widest audience possible. Director Christopher Nolan’s “Tenet,” another mind-bender in the tradition of “Inception,” is the biggie opening this week, with preview screenings already starting before its official, Sept.