A、The loss of elm trees in the 1970s. B、Dutch butterfly disease. C、Air pollution in Sheffield. D、Extinction of their colony. A

The tiny eggs of an endangered butterfly, the white-letter hairstreak, have been found in Scotland, suggesting the insect has returned to breed in the country for the first time in more than 130 years.
While most butterflies become worms in winter, the white-letter hairstreak spends nine months of the year as an egg, which is smaller than a grain of salt and stuck to slender branches of elm.
The eggs were detected by Jill Mills and Ken Haydock, volunteers for Butterfly Conservation who travelled from Bolton to search trees in the Borders.
The white-letter hairstreak has suffered a 72% decline over the last decade and is still suffering from the loss of elm trees in the 1970s caused by Dutch Elm disease.
A colony of the butterfly is threatened with extinction in Sheffield, where campaigners are fighting to save a rare surviving English elm. Sheffield council wants to drastically prune the tree as part of its controversial PFI contract to maintain the city’s streets. Butterfly Conservation is opposed to the pruning or destruction of the tree.
Questions 1 and 2 are based on the news report you have just heard.
1. What is special about the white-letter hairstreak?
2. What is the white-letter hairstreak still suffering now?