Option A;- Incorrect
Heartless human beings are like wild animals, which rip its own kin at the slightest of need. Singular pronoun for plural antecedent.

Option B ;- Incorrect
Heartless human being were like wild animals, which have ripped their own kin at the slightest of need. THE usage of PAST tense verb with PRESENT tense verb makes this sentence erred.

Option C;- Incorrect
Human beings are like heartless wild animal, which rip their own kin in the slightest of need. The point emphasis and the organic meaning of the real sentence have been truncated with this option. Not all human beings, but a class of them are the reference here.

Option D;- Incorrect
Human being are like heartless wild animals, which rip at its own kin in the slightest of need. This is similar to the mistake in the option A above. The use of its is a grammatical error. This causes a deviation in the true knowledge of the question.

Option E;- correct
Heartless human beings are like wild animals. which rip their own kin in the slightest of need. The subject verb agreement otherwise knows as concord and the brevity makes this option the best pick.