Step 1: Group the four options by what they actually are. Biotin, niacin and pantothenic acid are all B-vitamins required for normal metabolism, so none of them can be an anti-nutritional factor.
Step 2: That leaves phytic acid, which is a phosphorus storage compound in seeds. It chelates minerals such as iron, zinc and calcium, forming complexes the gut cannot absorb well.
Step 3: This mineral-binding action is exactly what defines an anti-nutritional factor, so phytic acid fits the description in pulses.
\[\boxed{\text{Phytic acid}}\]