Solution:
'was that he was too young'

Solution:
Change, of all animals → than any other animal In a comparative degree THAN is used. Also, the term of comparison must exclude the things compared by use of OTHER.

Solution:
I hear

Solution:
and personal attention to each child

Solution:
sometime next week

Solution:
you undertake

Solution:
The grammatical error is in the phrase "have not receptive". The word "receptive" is an adjective, but it is used incorrectly here. The correct form should be the adjective "receptive" followed by the preposition "to", forming the phrase "receptive to". Therefore, the correct phrase should be "have not been receptive to". So, the correct sentence should be: Generally, people have not been receptive to Therefore, the grammatically correct version of the sentence is obtained by replacing Option A with the corrected phrase.