The correct answer is A. Convert.
To expand something is to make it larger or more extensive. To convert something is to change it into something else. To condense something is to make it shorter or more compact. Tocongest something is to fill it up so that there is no room left. To conclude something is to bring it to an end.
In the context of the question, the correct answer is A. Convert. This is because the question is asking for a word that means “to make something larger or more extensive.” The other options do not mean this. Option B, condense, means to make something shorter or more compact. Option C,congest, means to fill something up so that there is no room left. Option D, conclude, means to bring something to an end.