In solid rocket motor terminology, a sliver is: a. a basic geometric shape b. leftover propellant c. a test article for propellant characterization d. a type of igniter

In the question given out of the four options

option B. Leftover propellant

is correct.

Explanation:

Solid rocket motors have rocket engines that uses solid fuels or propellants such as HTPB and PBAN as the most commonly used binders.

These rockets always have the propellant in adequate amount can be powered for long enough without much fuel degradation and therefore are reliable and mostly used in military applications.

Since these have fuel or propellant storage and therefore to indicate it, solid rocket motor identifies the left over propellant as ' a silver' .