Correct! Longissimus is one of the erector spinae group of muscles that run longitudinally along the spine. Strain of this muscle or it's attachments to the thoracolumbar fascia is consistent with lower back pain.

Additional pain while lifting an object is also consistent with this muscle injury as a function of the erector spinae group of muscles is to pull the spine erect.

Incorrect. The rhomboid muscles run between the medial border of the scapula and the spinous processes of the vertebra. Thus, these are located in the upper back, not lower. The rhomboids also function to pull the scapula towards the spine and are unrelated to spine flexion/extension movements.    

Incorrect. This condition involves ossification of intervertebral disks and possibly including other spine joints (facet, costovertebral, costotransverse, sacroiliac). The condition correlates with decreased flexibility, while this patient exhibits normal range of motion.

Incorrect. Lordosis is the normal curvature of the spine, when excessive there is increased curvature, in this answer of the lumbar spine. This is could be the result of increased abdominal mass (e.g. during pregnancy, however this patient is male). While not normal, lordosis in and of itself usually does not directly result in pain.

Correct! A lumbar radiculopathy from a herniated intervertebral disk could be putting pressure on spinal nerves causing lower back pain and referred pain that radiates to the affected nerve dermatome (e.g. down the posterior leg described here).

When flexing compression of the anterior part of the disk causes a posterior bulge exasperating the symptoms, while in extension the posterior disk is compressed displacing disk material anteriorly reducing symptoms.