English · Combination Mistake

The definition of an index is (in a book or set of books) an alphabetical list of names, subjects, etc. with reference to the pages on which they are mentioned.

'Lager' means beer. A ladder is a piece of equipment used for climbing up or down something. The step is an elevation. In this case, ‘ladder’ is the most suitable means to go up the roof, hence is correct. 

This is incorrect because an index is a list of information or terms, usually arranged in alphabetical order, to help locate specific information. It does not provide a means of reaching the roof of a house.

This is incorrect because "lager" refers to a type of beer, not a device or object used for climbing or reaching the roof.

The step is an elevation. In this case, ‘ladder’ is the most suitable means to go up the roof, hence is correct.  

This is incorrect because a "step" is a flat surface that allows you to move from one level to another, but it is not specifically designed for reaching higher places like a roof.