The correct answer is option 1: 1 and 4.

Let`s dissect each statement to understand why they are correct:

1. It is a megathermal region: This means that the Equatorial region has a high temperature throughout the year. The location of the Equatorial region near the equator results in high levels of solar radiation, which leads to consistently warm temperatures.

2. It is a sclerophyll region: This statement is incorrect. Sclerophyll regions are characterized by vegetation with hard and stiff leaves. The Equatorial region, on the other hand, is dominated by tropical rainforests with broadleaf evergreen trees and a variety of plant species.

3. It is a region of high development: This statement is incorrect. The level of development varies in the Equatorial region, just like any other region. Development depends on various factors such as political stability, economic resources, infrastructure, and social factors.

4. It is a region of aerial streamlets: Aerial streamlets refer to atmospheric phenomena like trade winds and monsoons. These winds are characterized by consistent, horizontal flows in the atmosphere. The Equatorial region experiences trade winds due to the Earth`s rotation and temperature differences between the equator and poles, making this