Final answer:
The phrase "one block of code may be nested in another" means that a block of code can be placed inside another block to create structured and complex logic within programs. The correct answer to the question is (A).
Step-by-step explanation:
The phrase "one block of code may be nested in another" refers to the concept where one block of code is written inside another block. This is a common practice in programming to create structure and control the flow of execution.
For example, in many programming languages, if-else statements, while loops, and for loops all create blocks of code that can contain other blocks. When a function is defined, the code within that function is also considered a block, which can have nested if-else statements or loops within it.
The correct answer to what is meant by the phrase is:
(A) A block of code can be placed inside another block of code. This is because nestable blocks allow more complex logic to be implemented by controlling when and how the inner blocks are executed in relation to the outer ones.