The muslims always beg . . . . . . . . Allah's help.

Answer: Option D

Beg for is used when someone asks or requests for a thing (help / support / assistance etc.)

In this sentence “Allah’s help” = the thing they are asking for

Therefore, the natural and grammatically correct preposition is for

Why not the other options?

of → used when requesting directly from a person (Example: “I beg of you”)

by → does not express a request in this usage

to → used in different meanings (Example: “I beg to differ”)

So the correct sentence is:

The Muslims always beg for Allah’s help.

Note: This sentence is only a grammar / preposition practice example. There is no religious intention or offence meant. If any word usage feels uncomfortable, it can be replaced with a neutral example — but grammatically, the structure “beg for (help)” remains the same.