Which of the following sets of three forces acting on a body cannot have a resultant of zero?

$A$ flexible chain of weight $W$ hangs between two fixed points $A$ and $B$ which are at the same horizontal level. The inclination of the chain with the horizontal at both the points of support is $\theta$. What is the tension of the chain at the mid point?

$A$ mass $M$ is suspended by a system of light inextensible strings as shown in the figure. Find the tension in the horizontal string.

Mr. $A, B$ and $C$ are trying to put a heavy piston into a cylinder at a mechanical workshop in a railway yard. If they apply forces $F_1, F_2$ and $F_3$ respectively on ropes,then for which set of forces at that instant will they be able to perform the said job?

When an object is at rest,

$A$ $1 \text{ N}$ pendulum bob is held at an angle $\theta$ from the vertical by a $2 \text{ N}$ horizontal force $F$ as shown in the figure. The tension in the string supporting the pendulum bob (in newton) is