Final Answer:
Flintlock (big men on big horses clad In lamellar armour and carrying flintlocks) B. Rifles
Step-by-step explanation:
Flintlock weapons were primarily used during the 17th to 19th centuries, and the term "flintlock" refers to the mechanism used to ignite the gunpowder. In this context, big men on big horses clad in lamellar armor carrying flintlocks would most likely be armed with rifles.
B.Rifles are characterized by a rifled barrel, which imparts a spin to the bullet, providing greater accuracy compared to muskets. The use of rifles by mounted troops was more common during the latter part of this historical period.
Rifles, with their longer barrels and grooved rifling, allowed for increased accuracy and effective firing at greater distances. This improvement in accuracy was crucial for mounted troops, as they needed to deliver precise shots from horseback. While muskets were prevalent earlier in this era, rifles gradually replaced them, offering better range and accuracy.
Cannons were large artillery pieces, typically not carried by individual cavalrymen, and sabers were edged weapons used in close combat, not firearms. Therefore, considering the era and the description of the weaponry, rifles emerge as the most suitable choice for big men on big horses with flintlocks.