This is a question with answer options. Goal: how do I make homemade guac?

Which of the following methods is more reasonable for accomplishing this goal?

OPT: (a). 1 extra large lemon diced 1 small vine-ripened tomato diced 1/2 red onion finely chopped 3 tablespoon coriander chopped Instructions Into a bowl, place all the ingredients. Season with sea salt and cracked pepper and gently mix to combine. Cover with glad wrap and refrigerate until ready to serve, though this dip is best served immediately to prevent the avocado oxidising.. (b). 1 extra large avocado diced 1 small vine-ripened tomato diced 1/2 red onion finely chopped 3 tablespoon coriander chopped Instructions Into a bowl, place all the ingredients. Season with sea salt and cracked pepper and gently mix to combine. Cover with glad wrap and refrigerate until ready to serve, though this dip is best served immediately to prevent the avocado oxidising.....I think the answer is
(b).