The possibility of fraternal twin occurs -

Correct option is A

The correct answer is (a) At fertilisation stage.
· Fraternal twins (dizygotic twins) occur when two separate eggs are fertilized by two different sperm during the fertilization stage.
· This leads to the development of two embryos that are genetically distinct from each other.
Additional Knowledge:
· At zygotic stage: Incorrect, the zygotic stage refers to the development after fertilization, but fraternal twins result from the fertilization of two eggs.
· Subsequent to fertilisation: Incorrect, fraternal twins form at the fertilization stage, not afterward.
· At conception: Incorrect, conception refers broadly to the moment when sperm meets egg, but the specific event for fraternal twins is the fertilization of two eggs.