Select from options: Continue writing the next sentence.

How to diagnose hookworms in dogs 
Be on the lookout for diarrhea or vomiting. 
A hookworm bites into the bowel wall, which can cause pain and stomach cramps. The dog is also likely to have diarrhea that is tinged with blood.

OPT:
A). Look for diarrhea that changes colors and thickens, especially when the dog eats frequently. If the dog is vomiting a lot, it may indicate hookworms.;
B). The feces may appear slightly pink, become yellow or look yellowish, and form thick bits. Your dog might also salivate or have a greenish ball in its stomach, which can be a sign of hookworm.;
C). Also, if there is bleeding into the bowel, by the time the blood have passed along the gut it gives the feces a dark color. Some dogs may also vomit from hookworms, and this could contain blood as well.;
D). To treat this it's a good idea to contact your vet. Be on the look out for diarrhea.;
Answer:
C).