The correct option is A later
'Later' and 'latter' are both comparative forms of the adjective 'late', but they differ in meaning. 'Later' is used in terms of 'time', and 'latter' means the second of the two people or things that were mentioned previously. Similarly, 'latest' and 'last' are the superlative forms of 'later' and 'latter', respectively. The given sentence is of the comparative degree of comparison. The comparative form of the word 'late' will be 'later', because the context of the sentence suggests that the speaker refers to the 'time', hence Option A is correct. Option B is incorrect because 'latest' is a superlative and the statement is a comparative. Option C is incorrect because 'latter' denotes the second of two things mentioned, and it isn't relevant to what the sentence conveys. Option D is incorrect because it is a superlative.