Choose the most grammatically correct sentence:

A. The organic link between the RSS and the BJP was never in doubt, but the relations between the two outfits had been tense in the past few years.

B. The organic link between the RSS and the BJP is never in doubt, but the relations between the two outfits have been tense in the past few years.

C. The organic link between the RSS and the BJP was never in doubt, but the relations between the two outfits would have been tense in the past few years.

D. The organic link between the RSS and the BJP were never in doubt, but the relations between the two outfits had been tense in the past few years.

E. The organic link between the RSS and the BJP was never in doubt, but the relationship between the two outfits have been tense in the past few years.