Overview: In order for an enhancement type N-MOSFET to function as a resistor, the gate of the MOSFET should be connected to the drain terminal. This configuration is known as a "depletion mode" operation, where the MOSFET operates in the linear region and acts as a variable resistor.

Explanation:

1. MOSFET Basics:
Before understanding the connection required for an enhancement type N-MOSFET to function as a resistor, let's briefly go through the basics of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor).

- A MOSFET is a three-terminal device that consists of a gate, a source, and a drain.
- The MOSFET operates by controlling the current flow between the source and drain terminals using the voltage applied to the gate terminal.
- The MOSFET can be operated in two modes: enhancement mode and depletion mode.

2. Enhancement Mode vs. Depletion Mode:
- In enhancement mode, the MOSFET is normally off, and a positive voltage applied to the gate terminal turns it on.
- In depletion mode, the MOSFET is normally on, and a negative voltage applied to the gate terminal turns it off.

3. Connecting the Gate to the Drain:
To function as a resistor, an enhancement type N-MOSFET needs to be operated in the depletion mode. This can be achieved by connecting the gate terminal to the drain terminal.

- When the gate and drain are connected together, the MOSFET operates in the linear region.
- In this configuration, the MOSFET acts as a variable resistor, and the resistance value is determined by the gate-to-source voltage (Vgs).
- By adjusting the Vgs, the resistance of the MOSFET can be controlled, allowing it to function as a resistor.

4. Other Options:
The other options mentioned in the question are not correct for using an enhancement type N-MOSFET as a resistor.

- Connecting the gate to the source (option A) would not allow the MOSFET to operate in the depletion mode.
- Connecting the drain to the source (option C) would short-circuit the MOSFET, preventing any resistance control.
- Ensuring that the drain voltage is less than the overdrive voltage (option D) does not guarantee that the MOSFET will operate as a resistor.

Conclusion:
To use an enhancement type N-MOSFET as a resistor, the gate should be connected to the drain terminal. This configuration allows the MOSFET to operate in the depletion mode, where it acts as a variable resistor.