Presidential form of government is a type of government where the executive branch is separate from the legislative branch. The head of state, known as the President, is elected by the people and holds significant powers and responsibilities. The features of a Presidential form of government are as follows:

1. Separation of Power:
- This is a fundamental feature of a Presidential form of government where the executive, legislative, and judicial powers are distributed among separate branches of government.
- The President is the head of the executive branch, while the legislature, which consists of the Congress or Parliament, is responsible for making laws.
- This separation of powers ensures the checks and balances system, where each branch acts as a check on the powers of the other branches, preventing any one branch from becoming too powerful.

2. Single Executive:
- In a Presidential form of government, there is a single executive who is elected directly by the people.
- The President holds significant powers and responsibilities such as making executive decisions, implementing laws, and representing the country both domestically and internationally.
- This single executive is accountable to the people and can be held responsible for their actions.

3. Wider Representation:
- One of the key features of a Presidential form of government is that it provides a wider representation of the people.
- The President is elected by the people through a direct election, ensuring that the leader has a popular mandate and represents the interests of the citizens.
- This form of government allows for the representation of diverse perspectives, as different political parties and candidates can contest the elections.

4. Stable Government:
- Unlike the assertion in the question, a Presidential form of government is generally considered to provide a more stable government.
- The President is elected for a fixed term and cannot be easily removed from office, ensuring stability and continuity in governance.
- Additionally, the separation of powers and the checks and balances system prevent any single branch of government from dominating the others, further ensuring stability.

In conclusion, the correct features of a Presidential form of government are separation of power and single executive, making option D the correct answer. This form of government provides a wider representation of the people and generally offers stability in governance.