a. I have known John for twenty-two years, <i>all of them in connection with business.</i><br/><br/><br/><br/>b. I have known John for twenty-two years, <i>all of them are in connection with business.</i><br/><br/><br/><br/>c. I have known John for twenty-two years, <i>all of which are in connection with business.</i><br/><br/><br/><br/>d. I have known John for twenty-two years, <i>all of which in connection with business.</i><br/><br/>Are all grammatical except b, which has a comma splice?<br/><br/>Which version is best?<br/><br/>Do you think the antecedents for the relative pronouns 'which' & 'them' are 'twenty two years' or the entire preceding sentence? <br/><br/>Thank you