This is done to achieve primary force

Question

In a 4–cyIinder 4–stroke inline IC engine the angle between two successive cranks should be 180°. But this rule is violated for cranks 2 and 3 (i.e. inner cranks) and the angle is made 0°. This is done to achieve primary force                      

(a) and secondary force balancing

(b) and secondary couple balancing

(c) Primary and secondary couple balancing

(d) Secondary force and primary couple balancing