Error spotting (exam direction): Identify the erroneous part (A/B/C) — choose D if there is no error — 'At present juncture / however, the supercomputer / would be a costly toy. / No error.'

Given sentence parts (A–D)
A. At present junctureB. however, the supercomputerC. would be a costly toy.D. No error.

Concept/Approach (fixed phrase with article)
The standard expression is 'at the present juncture'. The definite article is required.

Step-by-Step correction
1) Insert article: 'At present juncture' → 'At the present juncture'.2) Final sentence: 'At the present juncture, however, the supercomputer would be a costly toy.'

Verification/Alternative
Also acceptable: 'At present' (without 'juncture'), but with 'juncture' the article is necessary.

Common pitfalls
Dropping articles in set phrases.

Final Answer
A — 'At present juncture' → 'At the present juncture'.