the problem lies in not being able to see the main subject. ask yourself what is the verb and what is it affecting, the answer will give you the direct object. the directing verb is affecting the projects. The subject is plural theirfore plural verb which is seek. Seeks is singular and seek is plural. this information will eliminate c d and e. Now you are left with a and b. But if you look at b it sais the extent of ..... unidiomatic and b is concise direct answer.

keep your quesions coming my way these are kind of fun. also switch your questions over to the sentence correction section and out of math problem solving section. hope I answered your question my friend.