Final answer:
The rocker arm ratio in a pushrod engine affects the valve motion. A 1:5:1 ratio means that for every unit of lift on the camshaft, the valve opens by five units.
Step-by-step explanation:
A rocker arm is a mechanical component in an engine that helps transfer the camshaft's rotational motion to open the engine's valves. The 1:5:1 ratio means that for every unit of lift on the camshaft, the valve will open by five units, and the total valve lift will be five times the camshaft lift.
So, a cam lift of 0.250 inch would cause the valve to open by (0.250 x 5) inch, which is 1.250 inch. Therefore, Option 2) A cam lift of 0.250 will cause the valve to open 0.375 inch is incorrect.
The engine being fitted with hydraulic or roller lifters is unrelated to the rocker arm ratio, so Options 3) and 4) are incorrect. The rocker arm ratio only affects the valve motion.
Therefore, Option 1) A cam lift of 0.250 will cause the valve to open 0.188 inch is the correct answer.