Step 1: SDG 3 (target 3.1) sets the global goal for maternal health: by 2030, reduce the maternal mortality ratio to less than 70 per 100,000 live births.
Step 2: 100,000 live births equals 1 lakh live births. So the target is the same as less than 70 per lakh live births, which matches option a.
Step 3: Watch the denominator. MMR is conventionally expressed per 100,000 (per lakh) live births, not per 1000. So options c and d, which use per 1000, use the wrong denominator and are out.
Why not b: 100 per lakh is above the SDG ceiling of 70.
Ref: Park's PSM, 24th ed., Page 28, Table 4.