Consider the following four statements (a-d) and select the option which includes all the correct ones (a) Skeletal muscle fibre is a syncytium as the sarcoplasm contains many nuclei. (b) In the centre of each "I band" is an elastic fibre called H-line which bisects it. (c) In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments. (d) The contraction of a muscle fibre takes place by the sliding of the thick filaments over the thin filaments