The given graph shows length-tension curve for a typical vertebrate sarcomere.

By analysing the graph, what can you deduce regarding the muscle contraction?
(i) Neither the myosin filaments nor the actin thin filaments change in length when a sarcomere shortens or is stretched. Instead, it is the extent of ocerlap between actin and myosin filaments that changes.
(ii) The total tension produced by a sarcomere is proportional to the total number of cross-bridges that can interact with actin filaments, and this number in turn is proportional to the amount of of overlap between thick and thin filaments.
(iii) The tension produced by the muscle is maximal when the overlap between thick and thin filamentss allows the largest number of myosin cross-bridges to bind to actin.
(iv) Tension drops off with increased lenght, because the thick and thin filaments overlap less and fewer cross-bridges can bind.
Tension drops off with decreased length, because thin filaments at the two ends of the secromere begin to collide with each other, preventing further shortening.

Options

A. (i) Only
B. (i),(iii) and (iv)
C. (i),(iii),(iv) and (v)
D. (i),(ii),(iii),(iv) and (v)

Answer

D