The question asks which statement is legally accurate about criminal conspiracy under Section 120A of the IPC, 1860. Testing each statement against the statutory definition of conspiracy resolves this quickly.
Only the statement about serious offences needing nothing beyond the agreement itself accurately reflects Sections 120A and 120B; the others misstate the number of participants required or the effect of combining charges.
Therefore, the correct answer is The mere agreement between parties is sufficient to constitute the offence if the intended crime is punishable by death or rigorous imprisonment.