Electric force direction on negative charge

Steps:

• Recall the force formula: $\vec{F} = q\vec{E}$, where direction of $\vec{F}$ aligns with $\vec{E}$ for positive $q$, but opposes for negative $q$.
• The charge is negative and stationary, so force direction is opposite to electric field direction.
• Given force points right, electric field must point left to produce opposite force on negative charge.
• No other components (up/down) mentioned, so field is horizontal.

Why A is correct:

• For negative charge, $\vec{F} = q\vec{E}$ with means is opposite to ; rightward force implies leftward field.

Why the others are wrong:

• B: Rightward field would push negative charge left, not right.
• C: Downward field would force negative charge up, not right.
• D: Upward field would force negative charge down, not right.

Final answer: A