Answer:
the correct answer is option A- Intercalated disc
Step-by-step explanation:
Intercalated discs are the characteristic microscopic feature of the cardiac muscle which allows the cardiac cells to work as a single unit or syncytium.
The disc allows the cardiomyocytes (an individual cell) to act as one unit due to the "desmosomes and gap junctions" which allows the diffusion of ions to pass to nearby cardiomyocytes and allow depolarization of the entire heart which causes contraction.
Thus, option A- Intercalated disc is the correct answer.