The term "account corpus" refers to:

The term "account corpus" primarily refers to the principal amount in an investment account, which includes both principal cash and principal investments. This represents the core amount that is invested and from which returns can be derived. Understanding the corpus is essential as it forms the foundation for any income generated from an investment, such as interest or dividends.

In this context, the principal cash would denote any cash that has been invested initially, while principal investments encompass the value of stocks, bonds, or other assets held within the account.

Other options refer to various components of an investment portfolio but do not accurately encapsulate the meaning of "account corpus." The mention of income or total cash and investments expands beyond the definition of corpus, which is strictly concerned with the principal itself. Thus, the focus on principal cash and principal investments aligns perfectly with the definition of account corpus.