Concept:
- An antonym question needs the word OPPOSITE in meaning, not close in meaning.
- 'Lax' means careless, not strict, loose about rules or discipline.
Step 1: Fix the meaning of 'lax' from the sentence
The designer was 'lax' about training means he was careless and not strict about it.
Step 2: Check the options for closeness vs opposite
'Soft' and 'Lenient' actually mean almost the same as lax, not opposite. 'Casual' also matches lax, not its opposite. So these three are wrong direction.
Step 3: Pick the true opposite
'Strict' means firm and demanding proper discipline, which is the exact opposite of being lax.
Final Answer: Strict