Which of the following structures contract and relax rhythmically to produce movement?

The set of ions necessary for muscle contraction is

$I.$ Sarcoplasmic reticulum are abundant
$II.$ Myoglobin content is high
$III.$ Sarcoplasmic reticulum are moderate
$IV.$ Aerobic muscles
$V.$ Depends on anaerobic respiration for energy
$VI.$ Less myoglobin content
Select the option with correct statements for red muscle.

Assertion: Fatigue is the inability of a muscle to relax.
Reason: It is due to lactic acid accumulation by repeated contractions.

Actin filament is made up of

The sliding filament theory to explain muscular contraction was given by