(a) not a replace them by a single force
(b) to replace them by a single force
(c) to replace them by a single force through C.G.
(d) to replace them by a couple
(e) to replace them by a couple and a force.
Ans: b
(a) not a replace them by a single force
(b) to replace them by a single force
(c) to replace them by a single force through C.G.
(d) to replace them by a couple
(e) to replace them by a couple and a force.
Ans: b