To prevent long page load times for pages containing images, it is best to use a compressed file format such as JPG, as well as appropriate image dimensions and resolution.
magnification.
orientation.
colors.

The answer to this question is given below in the explanation section.

Explanation:

The given options to this question are:

The correct option to this question is 1. i.e.

Resolution.

The resolution of an image determines how many pixels per inch an image contains. Image having a higher resolution takes long page load times for a page and lower resolution takes less page load time. So, to prevent long page load times for pages containing images, it is best to use compressed file formation as well as appropriate image dimension and resolution.

While other options are not correct because:

Magnification, orientation, and color does not affect the page load time. Page load time for images only affected by the dimension and resolution of the images.