The sentence below is divided into three parts, marked A, B and C. A fourth…

Concept. A 'spot the error' item asks one question only: does some part of the sentence BREAK a rule of standard English grammar? A part that could merely be phrased differently is not an error — a stylistic preference is not a grammatical fault. The rule most often invoked by a sentence like this one is the in / into contrast: 'into' is the preposition of movement across a boundary, 'in' the preposition of position. What is decisive here is that standard reference grammar states this contrast is neutralised after a small set of verbs. Cambridge's grammar (In, into) puts it plainly: "With some verbs (e.g. put, fall, jump, dive) we can use either in or into with no difference in meaning" — "Can you put the milk in/into the fridge?"

Application — test each part against an actual rule.

1. A — 'The magician then put the five tiny': the determiner, numeral and adjective stand in the required order ('the five tiny') before the noun, 'then' is correctly placed before the verb, and 'put' is a correct simple past. No rule is broken. A part can read as incomplete simply because the sentence is cut mid-phrase; that is not a grammatical error.

2. B — 'balls back in his pocket and': this is where the trap is laid. The verb governing the preposition is 'put' — precisely one of the verbs Cambridge names as taking 'in' or 'into' with no difference in meaning. Longman's entry for 'put' records the corpus examples "I put the coin in my pocket" and "I put the letter back in the envelope" — the identical structure. So 'put ... back in his pocket' is standard English. 'into his pocket' would also be possible, but an available alternative wording is not a correction: nothing here is actually wrong.

3. C — 'the journey was resumed.': 'was resumed' is a correctly formed passive (auxiliary 'was' + past participle 'resumed'). This clause carries its own subject, 'the journey', so it is an independent clause, and two independent clauses joined by 'and' are free to differ in voice. An active-to-passive shift across different subjects is a matter of style, not a rule of grammar. No rule is broken.

Cross-check. Read the sentence straight through: 'The magician then put the five tiny balls back in his pocket and the journey was resumed.' Every verb agrees with its subject; the tense is consistently simple past; every preposition is one that its verb licenses; and no article, number or word-order rule is violated. There is nothing in the sentence that MUST be changed to make it grammatical.

Contrast — where the in/into rule really does bite:

• 'He divided the cake in two parts' → 'into two parts'. 'Divide' demands 'into', so there 'in' genuinely is an error.

• 'Translate this passage in English' → 'into English'. 'Translate' demands 'into', so there too 'in' genuinely is an error.

• But after put, fall, jump and dive, both 'in' and 'into' are correct — and 'put' is exactly the verb this sentence uses.

Result. No part of this sentence contains a grammatical error, so the sentence is sound as written and the answer is 'No error' — the choice marked D. The item is built to punish a half-remembered rule: a candidate 'fixes' 'in his pocket' to 'into his pocket' and picks the part containing it, but 'put' is one of the verbs for which 'into' is optional, never required.