Can we draw the following hypothesis from the context (see options)? 

Context:

Much against her will , Jo at length consented to sacrifice a day to Mrs. Grundy , and help her sister through what she regarded as ' a nonsensical business ' .<br>The invitations were sent , nearly all accepted , and the following Monday was set apart for the grand event .

Hypothesis: Jo has a sister. 
Choose from:
[A]. Yes;
[B]. It's impossible to say;
[C]. No;
[A].