In the Length-Tension Curve Shown, Why Does Force Decrease at Sarcomere

In the length-tension curve shown, why does force decrease at sarcomere lengths less than l_o?

A) Not as much Ca²⁺ is released in a sarcomere with a length less than l_o..
B) Interference between actin filaments originating from opposite ends of the sarcomere prevents maximal or optimal cross-bridge formation.
C) The muscle fiber runs out of ATP.
D) In this situation, Ca²⁺ availability and the position of the actin filaments are responsible for the decrease in muscle shortening because ATP will still be available.
E) All of these contribute to reduced muscle shortening in a sarcomere with a length less than l_o.