What is the standard form for the resolution of a vector having magnitude '`a`' and is inclined at an angle `theta` to the X axis?

Options

A. `a(cos theta hati + sin theta hatj)`
B. `a(sin theta hati + cos theta hatj)`
C. `a(sin theta hati + sin theta hatj)`
D. `a(cos theta hati + cos theta hatj)`