Find the grammatically correct sentence in standard, formal English among the…

Concept: A sentence is grammatically and idiomatically correct in standard English only when it avoids three common error classes tested here — verb-noun collocation mismatches (pairing the wrong verb with a noun, e.g. using ‘see’ instead of ‘have’ with ‘dream’), redundant or misplaced modifiers (adding an extra descriptive word — adjective or noun — that duplicates information already carried by another word), and confusing near-synonym adjectives that belong to different registers (e.g. ‘good’ describing moral quality versus ‘well’ describing physical health).

Application: Checking each option against these three error classes—

• 'The patient will be good soon.' describes a recovering patient, whose expected return to health is the natural reading here; standard formal English expresses that state with the adjective 'well,' not 'good' — this is the good/well confusion. General and informal usage does allow 'good' of health (as in 'I feel good'), but the stem asks specifically for standard, formal English, which is the register the official TPSC answer key applies here.

• 'This is a red colour rose.' inserts the noun 'colour' between the adjective 'red' and the noun 'rose,' duplicating the colour information already carried by 'red' — this is a redundant noun-modifier error.

• 'I saw a bad dream last night.' pairs the verb 'saw' with the object 'a bad dream,' where standard English collocation requires the verb 'had' — this is the verb-noun collocation error.

• 'Do not add fuel to the fire.' uses the standard negative-imperative structure with the correctly formed idiom 'add fuel to the fire,' and is free of all three error classes above under every natural reading.

Cross-check: Substituting the corrected forms confirms the pattern — 'will be well soon,' 'a red rose,' and 'had a bad dream' are the standard versions of the three flawed options, while 'Do not add fuel to the fire.' needs no such substitution.

Result: Because it violates none of the three standard-usage rules above, 'Do not add fuel to the fire.' is the grammatically correct sentence.