Hello. After a question introduced by the expression "the arising question is", which should be used: a period or an interrogative mark?<br/><br/>For example:<br/><br/>a) The arising question is how to deal with learning difficulties?<br/><br/>b) The arising question is how to deal with learning difficulties.<br/><br/>c) The arising question is: How to deal with learning difficulties?<br/><br/>Thank you!