It is astounding that a Ph.D. student could misspell the word “grammar.”Group of answer choicesadverb clauseadjective clausenoun clause

The clause "that a Ph.D. student could misspell the word “grammar”" is a noun clause.

Here's why:

1. A noun clause can act as a subject, an object, or a complement in a sentence. In this case, the clause is the object of the verb "is."

2. Noun clauses often start with words like "that," "what," "why," "if," and "whether," among others. In this case, the clause starts with "that."

3. Noun clauses can often be replaced with a single noun or pronoun to test if they are indeed noun clauses. If we replace the clause "that a Ph.D. student could misspell the word “grammar”" with the pronoun "it," the sentence still makes sense: "It is astounding." This confirms that the clause is a noun clause.