Consider the C struct defined below:struct data { int marks [100]; char grade; int cnumber; }; struct data student;The base address of student is available in register R1. The field student.grade can be accessed efficiently using

To access a specific field within a structure:

1. The base address of the structure variable student is fixed in register R1.

2. The member grade is located at a fixed compile-time byte offset from the start of the structure (specifically, the offset is after marks[100], which is $100 \times \text{sizeof(int)}$ bytes, plus any required padding/alignment).

3. In assembly/machine language, accessing an element at a fixed displacement from a base register is most efficiently performed using Base-Register / Indexed / Displacement addressing mode:

   $$\text{Effective Address} = \text{Base Register (R1)} + \text{Offset } X$$

   where $X$ is the constant offset.

Therefore, (D) is the correct option.