Two Statements are given followed by two conclusions numbered I and II. Assuming the statements to be true, even if they seem to be at variance with commonly known facts, decide which of the conclusions logically follow(s) from the statements.

Statements:

All crows are birds.

Some parrots are birds.

Conclusions:

I. No crow is a parrot.

II. Some crows are parrots.

The least possible Venn diagram for the given statements is as shown below :

Conclusions:

I. No crow is a parrot → Does not follow (As all crows are birds and some parrots are birds. So, as no direct negative or cross relation is given between crow and parrot therefore, it is definitely false)

II. Some crows are parrots → Does not follow (As As all crows are birds and some parrots are birds. So, it is possible but not definitely true)

∴ Here,

1. Elements i.e crow and parrot are same in both the conclusions.
2. Both the conclusions are individually does not follow(possible but not definitely true).
3. Conclusion I and II are complementary pair i.e Some and No

Hence, the correct answer is "Either conclusion I or II follows".

Additional Information Conditions of either or case

1. The elements should be same in both the conclusions
2. Both conclusions should possible but not definitely true.
3. One of the conclusion should be negative and one of the conclusion should be positive i.e complimentary pair.
4. Complimentary pairs :

• ​some + no and all + some not
• Some + Some not and All + no are not Complimentary pair.

Hence, the correct answer is "Either conclusion I or II follows".