The conflict in the question statement is that the moral system considers speaking the truth praise worthy only when there are significant incentives for telling lies. Then the author adds that speaking the truth out of habit is also praiseworthy In order to solve this discrepancy, we have to show that the second statement is not contradictory to the first. This is done in option (b). It effectively demonstrates that the second condition is actually a subset of the first condition. Option (a) is incorrect. It has no impact on the discrepancy and is pnmarily providing a reason for why people speak the truth. Option (c) is beyond the scope of information offered in the question statement. Option (d) is similar to option (a), as it also does not solve the discrepancy mentioned in the question statement.