Multi-choice problem: Continue writing the next sentence in this paragraph:

How to diagnose and treat the cause of deformed cat nails
Look for thicker nails.
The nails of cats should be thin and sharp, not thick. If your cat's nails become thicker and harder, this may be a symptom of an underlying health problem.

Choose from:
a). Older cats can develop thicker nails as they age. Thickening of the nails sometimes occurs with an increase thirst.
b). You should look for a consistency of coarse and angular nails in your cat's home. Mature cats will have thicker nails than younger cats.
c). It is normal for nails to grow thicker, whereas a cat with nails slightly thicker should have signs of depression and other behavioral problems. Hair loss at the top might indicate a health problem.
d). Signs to look for include : Yellowing nails looking like lumps or spots. Watch your cat's nails closely.
a).