A body at rest under action of 3 forces 2 of which are (𝑭𝟏 ) ⃗=𝟔𝒊 ̂ (𝑭𝟐 ) ⃗=𝟔𝒋 ̂ the 3rd force is:

A body is at rest under the action of three forces, two of which are (𝑭_𝟏 ) ⃗=𝟔𝒊 ̂ (𝑭_𝟐 ) ⃗=𝟔𝒋 ̂ the third force is:
(A) 𝟒𝒊 ̂+𝟔𝒋 ̂ (B) 𝟒𝒊 ̂−𝟔𝒋 ̂
(C) −𝟒𝒊 ̂+𝟔𝒋 ̂ (D) −𝟒𝒊 ̂−𝟔𝒋 ̂
Answer:
(D) −𝟒𝒊 ̂−𝟔𝒋 ̂