Chad was finding it difficult to remember the name of the scientist who developed the general theory of relativity. Chad's professor told him that the scientist's name begins with the letter "A." Chad soon remembered and said that the name of the scientist is Albert Einstein. In this scenario, the letter "A" serves as:

Spelling mnemonic

Explanation:

mnemonics are different strategies by which we can retain memory and make recalls when necessary. These mnemonics serve to recall the said memory whenever it is required by the person to do so.

In a spelling mnemonic one recalls things by remembering certain aspects of its spelling.

Like in this case, Chad is able to recall the name of the  scientist after he hears the first letter of his name, so it helped him remember the information.

answer; knowledge,reason,and judgement;