Which one of the following is not an argument ?

Concept: An argument is not merely a statement. It is a set of statements in which one or more statements, called the premises, are put forward as reasons for accepting another statement, called the conclusion. What makes a passage an argument is this inferential move from an asserted premise to a conclusion, and in ordinary language it is signalled by indicator words such as so, therefore, hence, since, because and must be.

Concept (continued): A conditional or hypothetical statement of the form 'If P, then Q' is a single compound proposition. It asserts only a link between the antecedent P and the consequent Q; it does not assert that P is true and it does not assert that Q is true. Because nothing is asserted as a reason, nothing is inferred from anything, so a conditional standing on its own is a statement and not an argument.

Application: compare the four statements by the expression that links their clauses and by what each one actually asserts.

Result: three of the statements assert a premise and draw a conclusion from it, so each of those three is an argument. The statement 'If Devadutt is growing fat and if he does not eat during the day, he will be eating at night' asserts no premise and draws no conclusion, so it is the one that is not an argument.

Cross-check: try rewriting each statement in the canonical form 'P, therefore Q'. The three that use so or since rewrite directly, because a premise is already asserted in them. The conditional cannot be rewritten in that form without first adding an assertion of its own antecedent, and that missing assertion is exactly what an argument requires.

Point to note: an argument may be weak or even fallacious and still be an argument. Concluding that Devadutt eats at night merely because he does not eat in the day is poor reasoning, but it is still reasoning; whether an argument is good is a separate question from whether an argument is present at all.