The sparring parts for this laptop have been continuously from producing.

​ In the sentence, the verb 'sparring' which means 'make the motions of boxing without landing heavy blows, as a form of training' is contextually irrelevant, the adverb 'continuously' is used in the place of a verb and the verb 'producing' is used in the place of a noun. In options (a) and (b), the base verbs suggested, 'discontinue' and 'stop' do not agree with the Present Perfect tense 'have been' of the sentence and the verb is required to be in the Past participle form (V3) since the given sentence is in passive voice. Thus, these two options cannot fit into the sentence, so they are negated. In option (c), the noun 'continuation' is suggested in place of a verb. Therefore, this option too does not fit into the sentence and gets negated. In option (d), the adjective/verb/noun 'spare' ['adjective' here] which means 'additional to what is required for ordinary use' qualifies the noun 'parts', the verb 'stopped' is in past participle form (V3) which agrees with the Present Perfect tense and passive voice of the sentence, and the noun 'production' denotes from what the spare parts are stopped. This option fits into the sentence contextually and grammatically. Hence, the correct answer is option (d).