All of the guests HAD gone to the concert in the park.
(But I think it could also be have, if you are talking about it happening in the present).
Gracias por su ayuda. Me ayudo mucho en mis puntos
The correct answer for the question that is being presented above is this one: "b. Mary had heard herself mentioned to Miss Bingley as the most accomplished girl in the neighbourhood; and Catherine and Lydia had been fortunate enough never to be without partners, which was all that they had yet learnt to care for at a ball"
