Floor of posterior triangle of neck is formed by: (A) Semispinalis capitis, elevator scapulae, scalenus anterior, scalenus medius, (B) Levator scapulae, splenius capitis, scalenus medius, scalenus anterior, (C) Semispinalis capitis, scalenus anterior, splenius capitis, sternocleidomastoid, (D) Levator scapulae, scalenus posterior, semispinalis capitis,scalenus medius
Answer is D. Muscles forming floor of posterior triangle of neck :

 Semispinalis capitis.
 Splenius capitis.
 Levator scapulae.
 Scalenus posterior.
 Scalenus medius.