The type of lava least likely to form a pyroclastic flow is
a.) basaltic
b.) andesitic
c.) rhyolitic

(A) Basaltic

Explanation:

 Basaltic is the type of the lava least that are likely to formed the pyroclastic flow. The basaltic word is comes from the Ethiopian origin  which means "black stone". The basaltic is the type of flow that are voluminous, non eruption and has low viscosity.

The pyroclastic flow is the type of flow which is associated with the silicic magma but the basaltic is associated with the magma. The basaltic magma basically contain the less number of the gaseous components.

Therefore, Option (A) is correct.  

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