In B, 'their' not 'whose' means the last 2 clauses are coordination clauses rather than subordination clauses. However, the last 2 clauses don't express coordination meaning with the main clause. To modify B, replace 'their' by 'whose' and delete the first 'and'. But it still sounds unidiomatic. A applys so called 'absolute structure' thus solve the dilemma. 请高手指正。