The sentence is split into four parts labelled a, b, c, and d. Choose the part that contains a grammatical error.

The foundation is striving steadily to raise the standard of the literacy in isolated communities.

The correct option containing the grammatical error is of the literacy.

Step-by-Step Explanation:
1. Analyze the sentence structure: The sentence discusses an organization working to improve reading and writing capabilities in remote areas.
2. Examine the noun "literacy": "Literacy" is an abstract, uncountable noun representing a general concept or state of being able to read and write.
3. Apply article usage rules: In English, abstract uncountable nouns used in a general sense do not take the definite article "the". Adding "the" before "literacy" is grammatically incorrect.
4. Correction: The phrase should omit the article "the" and simply say "of literacy".

Corrected sentence: "The foundation is striving steadily to raise the standard of literacy in isolated communities."

Hence, the part containing the error is of the literacy.