__________ small specimen of the embryonic fluid is removed from a foetus, it will be possible to determine whether the baby will be born with birth defects.

That a

If a

When it is a

None of these

Explanation

The sentence implies a condition for determining birth defects, which is best introduced by "If a."

"If a small specimen of the embryonic fluid is removed from a foetus, it will be possible to determine whether the baby will be born with birth defects" is grammatically and contextually accurate.