Concept:
Let us systematically scrutinize the sentence for grammatical accuracy across all components by checking spelling, modification, agreement, and structure.
Recombining the segments sequentially:
"A teacher’s primary duty is to guide and facilitate the learning process systematically."
Let us verify each segment step-by-step:
• Part A: "A teacher’s primary duty is" — The use of the possessive apostrophe-s (teacher's) is correct to show that the duty belongs to a teacher. The singular subject noun "duty" correctly matches with the singular auxiliary verb "is". This section is structurally sound.
• Part B: "to guide and facilitate the learning" — This introduces a parallel infinitive phrase: to guide and [to] facilitate. Both verbs are in their base form following the infinitive marker "to", which is correct. "The learning" functions correctly as a pre-modifier or gerundial noun for the upcoming word.
• Part C: "process systematically" — "Process" combines with "learning" to form the compound noun phrase "learning process", which acts as the direct object of the verbs. The word "systematically" is an adverb that correctly modifies the actions of guiding and facilitating.
Since all parts conform to standard English grammar rules, there are no structural errors or spelling issues. Therefore, Option (D) is the correct choice.