A gale-force solar storm that hit the Earth on March 13, 1989, sent electrons arcing across power lines, railroad tracks, and expanses of iron-bearing rock in eastern Canada, where alarmed engineers tried but failed to keep the Hydro-Quebec power grid operating.
|(A)||tried but failed to keep|
|(B)||tried but failed in their keeping|
|(C)||had tried but were failing in keeping|
|(D)||were trying but having failed to keep|
|(E)||were trying but they had failed in keeping|