Question

all the animals within the phylum chordata... are cold - blooded. have a well - developed brain. possess all these traits. have limbs.

Explanation:

• Cold - bloodedness (ectothermy) is not a universal trait in Chordata. For example, birds and mammals (which are chordates) are endothermic (warm - blooded).
• Not all chordates have well - developed brains. Simple chordates like lancelets have a relatively simple nervous system.
• Limbs are not present in all chordates. For example, fish (a large group within Chordata) may have fins instead of limbs in the traditional sense, and some chordates like hagfish are limbless.

Answer:

None of the options provided are correct as none of the traits (cold - blooded, well - developed brain, having limbs) are universal to all animals within the phylum Chordata.