Under-reamed piles are generally

ANS:B - bored piles

Under reamed pile are bore piles because we can't driven them in soil as they have bulb, so first we make boring then place concrete. These piles also known as bored piles. Under reamed piles first time made in India by the IIT Roorkee. Bulb are desined to increase the bearing capacity, spacing of bulb is also an important Parameter. It is found that under-reamed piles provide an ideal solution to foundation in black cotton soil or other similar types of expansive soils.