From which type of clouds do hail pelets form

The pellets are usually formed around a nucleus composed of ice when it collects cloud droplets or drops of rain. In rare cases, several pellets can clump together and give birth to irregular clumps known as giant hail. The nuclei themselves are cumulus clouds supercooled water droplets or ice crystals.

Explanation:

Cumulonimbus

Explanation:

because Ideal conditions for hail formation are very high clouds with intense updrafts, containing a large quantity of supercooled water (liquid water under 0°C) and with dust particles in the atmosphere.