The tense of a sentence denotes a time, whether it is the time now (present), time then (past) or the time to come (future). The verb of a sentence has most to do with the tense. In the given sentence, we need to fill in a word that determines the correct tense. The action in this sentence pertaining the market, completed in the past, and we know this as it's mentioned "last week", hence a verb in the simple past tense is required. 'Went' is in the simple past tense, and refers to the action (of going to the market) that completed in the past, hence option B is correct. 'Was go' is grammatically incorrect, as 'was' is used in the past continuous tense 'was going' and 'go' is used in the simple present tense 'I go to the market every week'. Hence option A is incorrect. 'Did go' is in the simple past tense, but it's usually used in the negative form 'did not go', hence option C is incorrect. 'Goed' is not a word, the past tense of 'go' is 'went', hence option D is incorrect.