The correct option is C No change
While framing any sentence, the basic rule is - Subject + verb + object (if any). 'I' is the subject, 'carry' is the verb and 'tiffin box' is the object. 'Always' is an adverb of frequency. The rule says that if a sentence has one verb, place the adverb of frequency in the middle of the sentence so that it is positioned after the subject but before the verb. Thus, according to the rule, option C is the correct answer as the given sentence is correct and requires no correction.