In skeletal muscle, the area that is composed only of both thick and thin filaments is the
a. a-band
b. i-band
c. h-zone
d. sarcomere
e. synapse

A-Band

Explanation:

Sarcomere is the basic unit of skeletal muscle and shows various striations under the microscope.

Anisotropic band or A-Band is the portion of sarcomere that contains both the thick and thin filaments . A-Band appaers dark under the microscope. Thick filaments are consist of actin and thin filaments consists of myosin.

I-Band contains only thin filaments of myosin. H- zone contains only thick filaments and no thin filament. Sarcomere is the unit of a skeletal muscle. Synapse is the junction between two neurons.

Thus, the correct answer is option (A).