Bertha,from Chicago,traveled to San Francisco to Attend a Conference

Bertha,from Chicago,traveled to San Francisco to attend a conference.Her sister,Martha,lives in San Francisco and consequently,Bertha made arrangements to spend a couple of days with her sister.The next morning sitting at the breakfast table,Bertha realizes that she packed a mismatched pair of shoes (one is black and the other is blue) .Luckily,Martha wears the same size of shoes and lends Bertha a pair of black leather pumps.During the day,the shoes are damaged while Bertha is wearing them.Bertha's duty of care would be a duty of

A) extraordinary care,because this is a bailment for the sole benefit of the bailee.
B) ordinary care,because this is a bailment with both parties receiving mutual benefits.
C) only slight care,because this is a bailment for the sole benefit of the bailor.
D) none,as the sisters would share without condition.