Anmol lives near a pond. She always notices tadpoles in the water but no frogs.What do you think is the reason?

Your friend is correct,

The possible reason may be the unfavourable conditions by which the complete metamorphosis of tadepole into adult frog does not occur. 

These unfavorable conditions may be: 

• Less availability of nutrients and space in the pond.
• Pollution of the pond water.
• Large number of predators in the pond etc.

@Amit......good work..Keep posting!