B.
      I live in a historic neighborhood in the heart of Washington, D.C. It’s not historic in the sense that anything especiallyimportant happened here — certainly not in the modest rowhouses that make up the bulk of the neighborhood. What “historic”means, here and in cities across the country, is that this is a neighborhood where buildings are not supposed to change. The lawsays window frames on Capitol Hill must be wooden, or something that looks very much like wood. If a front door has two partsand opens down the middle, it cannot be replaced by a single door that swings open from the side. If the house was built two storiestall, it must remain two stories tall — unless the addition can’t be seen from the street. Humans don’t like change, so it’s notsurprising that historic preservation laws have become quite popular. There are now more than 2,300 local historic districts acrossthe United States, and I know many people who would like to have their own neighborhood frozen in time.
      But historic preservation comes at a cost: It obstructs change for the better. And while that price is generally invisible, it isnow on public display because of the city’s efforts to prevent Washington homeowners in historic neighborhoods from installingvisible rooftop solar panels. As you may have heard, Earth is getting hotter because we’re burning too much carbon, and one smallway people can reduce their use of carbon is to tap the sun for electricity. I haven’t taken a poll, but I’m prepared to wager mostresidents of Washington’s historic districts agree that climate change is caused by humans and that we really ought to do somethingabout it. But the mandarins of historic preservation regard allowing people to install rooftop solar panels with the kind of horrorthey usually reserve for anachronistic window frames.
      “I applaud your greenness, and your desire to save the planet. And I realize that we are in crisis, politically as well assustainably,” Chris Landis, an architect who sat on one of the boards that pass judgment on proposed changes to Washingtonhomes, told a homeowner in October who had the temerity to request permission to install 12 front-facing solar panels on his ownroof. “But I just have this vision of a row of houses with solar panels on the front of them and it just — it upsets me, as somebodywho’s supposed to protect the architectural fabric of a neighborhood.”
      Mr. Landis and I apparently don’t share a sense of the sacrifices that may be required in a crisis. As the petitioner, StevenPreister, put the matter to Mr. Landis and his colleagues: “If we do not change and loosen these standards, will the district behabitable in 100 years?” Good question! The board, however, decided it was more important to keep Mr. Preister’s roof lookingas it did 100 years ago.
41. What does the passage mainly discuss?
(A) The preservation of historical buildings.
(B) The petition for installing roof solar panels.
(C) The architect’s praise of the green idea and his support of the petition.
(D) The conflict between historic preservation and environmental protection.