Limpets and Urchins Are Both Algal Grazers

Limpets and urchins are both algal grazers. If limpets tend to eat smaller algae, while sea urchins eat both large and small sizes, we say that

A) limpets have a smaller realised niche.
B) limpets and urchins are aggressively interfering with each other.
C) limpets and urchins are not competing.
D) urchins have a greater niche breadth.
E) limpets and urchins co-habitat.